/* === PHYSL 210 — imported practice exams + coverage cards + staged-deck wiring (auto-generated) === Additive & idempotent. Merges into window.QUESTIONS / FLASHCARDS / EXAMS. Sources: official practice exams (sources/practice-exams/), Opus-verified answers; coverage cards verified vs Vander 16e + course notes. */ (function(){ if (window.__physlExtraLoaded) return; window.__physlExtraLoaded = true; const PRACTICE_PAPERS = { "mid1-paper": { "id": "mid1-paper", "name": "1st Midterm — full paper", "mins": 45, "hue": 46, "cover": [ "cell", "blood", "nms" ], "desc": "The official 1st midterm (35 Q): Cell, Blood, Nerve/Muscle/Synapse physiology.", "questions": [ { "q": "Which one of the following statements regarding signal transduction is CORRECT? (cAMP = cyclic AMP)", "options": [ "Lipid-insoluble (water-soluble) chemical messengers bind to receptors in the cytoplasm or the nucleus.", "G-proteins are only stimulatory, activating cellular enzymes.", "Steroid hormones may act as transcription factors in the nucleus of the cell to alter the rate of protein synthesis.", "In the cAMP second messenger system, phosphodiesterase terminates the actions of cAMP by converting it back to ATP.", "The beta subunit of the G-protein binds GDP/GTP." ], "a": 2, "e": "Steroid/thyroid hormones bind intracellular nuclear receptors and alter gene transcription (act as transcription factors). A wrong: lipid-INsoluble messengers bind surface receptors. D wrong: cAMP→AMP not ATP. E wrong: ALPHA subunit binds GDP/GTP.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "Receptor-mediated endocytosis:", "options": [ "uses phagosomes which fuse with lysosomes to digest engulfed bacteria.", "is a process used by white blood cells to digest foreign bacteria.", "internalizes ligands found in low concentrations outside the cell.", "is a nonspecific process, binding any molecule that is in close proximity to a membrane-bound receptor.", "uses clathrin which functions as a membrane-bound receptor to bind ligands at the extracellular surface of the cell." ], "a": 2, "e": "Receptor-mediated endocytosis binds specific ligands with high affinity, letting cells internalize molecules present in low concentration. A/B = phagocytosis (WBC/bacteria); D = nonspecific pinocytosis; E wrong: clathrin is a cytosolic coat protein, not the receptor.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements regarding the movement of substrates across a membrane is CORRECT?", "options": [ "The GLUT family of proteins moves glucose across the membrane, down its concentration gradient, without the input of energy.", "The most important factor influencing the rate of simple diffusion is the membrane surface area.", "The process of exocytosis removes lipids and proteins from the plasma membrane.", "A sodium (Na+) ion will cross the phospholipid bilayer easily by simple diffusion.", "The Na+/H+ exchanger is an example of an electrogenic transport process." ], "a": 0, "e": "GLUT transporters move glucose down its gradient by facilitated diffusion, no ATP. B wrong: gradient is most important, not surface area. C wrong: exocytosis ADDS membrane. D wrong: charged Na+ doesn't cross bilayer freely. E wrong: Na+/H+ exchange is electroneutral.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements regarding the cell is CORRECT? (SER = smooth endoplasmic reticulum)", "options": [ "Cisternae are sets of flattened slightly curved membrane bound sacs stacked in layers which are found in mitochondria.", "The cytoskeleton is a membrane-bound organelle which functions to maintain organelle position.", "Lysosomes contain hydrolytic enzymes which are active at a neutral pH (pH 7.5).", "Peroxisomes contain catalase, which directly breaks down fatty acids, alcohol and drugs.", "The SER is important for synthesizing lipids, such as fatty acids." ], "a": 4, "e": "Smooth ER synthesizes lipids (e.g., fatty acids), detoxifies, stores Ca2+. A wrong: cisternae are Golgi, not mitochondria. B wrong: cytoskeleton is non-membranous. C wrong: lysosomes are acidic. D wrong: catalase destroys H2O2, doesn't directly break down fatty acids.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "The plasma membrane:", "options": [ "has phospholipids which may contain saturated fatty acid tails, meaning they contain double bonds.", "is impermeable to lipid-soluble substances.", "has extrinsic proteins such as the Na+/K+ pump.", "has glycoproteins which contribute to formation of the glycocalyx, which is important for identification between cells.", "has glycolipids which maintain proper fluidity of the plasma membrane." ], "a": 3, "e": "Glycoproteins form the glycocalyx, whose surface carbohydrates enable cell-cell recognition. A wrong: saturated = NO double bonds. B wrong: membrane IS permeable to lipid-soluble substances. C wrong: Na+/K+ pump is integral, not extrinsic. E wrong: cholesterol, not glycolipids, regulates fluidity.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following regarding cell junctions is CORRECT?", "options": [ "Desmosomes contain plaque proteins located at the extracellular surface of the cell which serve as anchoring points for cadherins.", "Gap junctions enable nutrient exchange between bone cells near the bloodstream and those embedded deeper within the tissue.", "Tight junctions contain occludins which provide structural integrity to the tissue.", "Desmosomes contain connexons which allow small molecules and ions to move between cells.", "Gap junctions contain cadherins which link cells together." ], "a": 1, "e": "Gap junctions are connexon channels linking cytosols, letting small molecules/ions pass between cells (e.g., osteocytes near vessels feeding deeper cells). A wrong: plaques are cytoplasmic. C: occludins seal, not structural integrity. D wrong: desmosomes use cadherins. E wrong: gap junctions use connexins.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "In the Ca2+-calmodulin signaling cascade:", "options": [ "Calmodulin exists continuously in its activated state within the cytoplasm, independent of intracellular Ca2+.", "Calmodulin functions as an enzyme embedded within the plasma membrane, directly phosphorylating downstream targets.", "The Golgi apparatus acts as the major intracellular reservoir of Ca2+, facilitating its rapid mobilization upon ligand stimulation.", "Ca2+ serves as a primary extracellular messenger, initiating signal transduction via G-protein coupled receptor (GPCR) interactions at the plasma membrane.", "Upon Ca2+ binding, calmodulin induces conformational changes that selectively regulate intracellular protein kinases." ], "a": 4, "e": "On binding Ca2+, calmodulin changes shape (conformational change), enabling Ca2+-calmodulin to selectively activate/inhibit target protein kinases. A wrong: calmodulin needs Ca2+. B wrong: it's cytosolic, not a membrane kinase. C wrong: ER/SR is the Ca2+ store. D wrong: Ca2+ is an intracellular second messenger.", "_mod": "cell", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following is CORRECT for a person with Type A blood? The person:", "options": [ "has anti-A antibodies in their plasma.", "has surface antigen B on their red blood cells.", "can safely donate blood to a person with Type O blood.", "can safely donate to a person with Type AB blood.", "has neither anti-A nor anti-B antibodies in their plasma." ], "a": 3, "e": "Type A has antigen A on RBCs and anti-B antibodies in plasma. A donor can safely give to an AB recipient because AB plasma lacks anti-A and anti-B antibodies (AB = universal recipient). Other options misstate antigens/antibodies; cannot give to type O (O has anti-A).", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "During hemostasis, platelets adhere to exposed collagen in blood vessels using __________. The platelets release __________, causing further platelet aggregation.", "options": [ "von Willebrand factor; ADP", "von Willebrand factor; nitric oxide", "ADP; thromboxane A2", "thromboxane A2; ADP", "thromboxane A2; nitric oxide" ], "a": 0, "e": "Platelets adhere to exposed collagen via von Willebrand factor (vWF bridges collagen and platelets), then release ADP (and serotonin) to drive further platelet aggregation. NO inhibits aggregation; thromboxane A2 augments but adhesion is vWF-mediated.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Plasmin is a key enzyme in the process of:", "options": [ "opsonization.", "hemolysis.", "agglutination.", "fibrinolysis.", "hematopoiesis." ], "a": 3, "e": "Plasminogen is activated to plasmin, which digests fibrin to dissolve clots: the fibrinolytic (thrombolytic) system. Plasmin is not involved in opsonization, hemolysis, agglutination, or hematopoiesis.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements about the destruction of red blood cells (RBCs) is CORRECT?", "options": [ "Macrophages in the bone marrow destroy old and damaged RBCs.", "Bilirubin is processed in the kidneys for excretion in the feces.", "Iron from heme is completely excreted in the urine or feces.", "Amino acids derived from the globin portion may be used in metabolic pathways.", "The globin portion of heme is broken down to biliverdin." ], "a": 3, "e": "Hemoglobin is split into heme and globin; globin is degraded to amino acids reused in metabolic pathways. RBCs are destroyed in spleen/liver (not bone marrow), iron is recycled via transferrin (not excreted), and heme (not globin) is oxidized to biliverdin then bilirubin (processed by liver, not kidneys).", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Complement proteins:", "options": [ "help in the formation of membrane attack complex.", "initiate activation of the blood clotting pathway.", "can act as pattern recognition receptors.", "help in antigen presentation.", "are responsible for acquired or adaptive immunity." ], "a": 0, "e": "Complement proteins help form the membrane attack complex (MAC), which lyses pathogens. They are innate effectors: they do not initiate clotting, are not pattern-recognition receptors (PRRs/TLRs are), do not present antigen (APCs do), and are not responsible for adaptive immunity.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements regarding B cell mediated immunity is CORRECT?", "options": [ "B cell mediated immunity is non-specific.", "B cells play a role in natural or innate immunity.", "B cells require the foreign antigen to be presented in a unique manner, known as \"antigen presentation\", to stimulate clonal expansion.", "B cells differentiate into plasma cells to synthesize antigen-specific antibodies.", "Memory B cells are short-lived (a few days) and are involved in the primary immune response only." ], "a": 3, "e": "Activated B cells differentiate into plasma cells that secrete antigen-specific antibodies (humoral immunity). B-cell immunity is specific and adaptive (not innate/non-specific); B cells bind free native antigen directly via membrane Ig and do NOT require antigen presentation (T cells do); memory B cells are long-lived.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following statements about the prothrombinase complex is CORRECT?", "options": [ "It catalyzes the degradation of prothrombin into inactive fragments.", "It includes factor VIIa as a key enzymatic component.", "It consists of factor Va, factor Xa, calcium ions, and a phospholipid surface.", "It initiates fibrinolysis during the resolution of a clot.", "It functions exclusively within the extrinsic pathway of coagulation." ], "a": 2, "e": "The prothrombinase complex = factor Xa + cofactor factor Va + Ca2+ on a phospholipid (platelet) surface; it converts prothrombin to thrombin (not degrades it). It contains Xa not VIIa, does not initiate fibrinolysis, and operates in the common pathway (not exclusively extrinsic).", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Platelets have __________ and are fragments of cytoplasm derived from __________. Platelets contain vesicles called alpha granules which release __________.", "options": [ "a multi-lobed nucleus; monocytes; ATP and ADP", "no nucleus; megakaryocytes; ATP and ADP", "no nucleus; megakaryocytes; von Willebrand factor (vWF)", "a multi-lobed nucleus; megakaryocytes; von Willebrand factor (vWF)", "no nucleus; monocytes; ATP and ADP" ], "a": 2, "e": "Platelets are nonnucleated cytoplasmic fragments pinched off from megakaryocytes. Alpha granules contain vWF, fibrinogen, and factor V; ADP/ATP are stored in dense (delta) granules, not alpha granules.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements regarding macrophages is NOT CORRECT? They:", "options": [ "are the major cells involved in adaptive or acquired immunity.", "recognize bacteria using their pattern recognition receptors or toll-like receptors.", "originate in the blood as monocytes.", "are effective phagocytic cells found in tissue spaces.", "present foreign antigens on MHC II proteins to helper T cells." ], "a": 0, "e": "NOT CORRECT: lymphocytes (not macrophages) are the major cells of adaptive immunity; macrophages are innate phagocytes. The other four are true: TLR recognition, derived from blood monocytes, tissue phagocytes, present antigen on MHC II to helper T cells.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Innate or natural immunity:", "options": [ "is slow to develop, occurring within days or weeks.", "develops in response to exposure to a specific foreign antigen.", "involves phagocytes such as neutrophils.", "involves cytotoxic molecules.", "involves B and T cells." ], "a": 2, "e": "Innate immunity involves phagocytes such as neutrophils. It is rapid/nonspecific; slow development, specific-antigen response, and B/T cells describe adaptive immunity. Cytotoxic molecules (cytotoxic T cells) are adaptive.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "The effect of aspirin in platelets is to:", "options": [ "cause the irreversible inhibition of COX1.", "increase the activity of COX1 (cyclooxygenase enzyme 1).", "cause the irreversible inhibition of COX2.", "increase the activity of COX2 (cyclooxygenase enzyme 2).", "increase the production of arachidonic acid." ], "a": 0, "e": "Aspirin irreversibly inhibits platelet COX1. Because platelets cannot synthesize new protein, thromboxane A2 production is lost for the platelet's lifetime, reducing aggregation. It inhibits (not increases) COX activity.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Intrinsic factor (IF) is a protein secreted by cells of the __________. The function of IF is to bind __________, which is necessary for its absorption. A deficiency of the absorbed substance results in __________.", "options": [ "stomach; vitamin B12; hemolytic anemia", "stomach; iron; pernicious anemia", "stomach; vitamin B12; pernicious anemia", "kidneys; iron; hemolytic anemia", "kidneys; vitamin B12; pernicious anemia" ], "a": 2, "e": "Intrinsic factor is secreted by the stomach and binds vitamin B12 to enable its intestinal absorption; deficiency causes pernicious anemia. Direct textbook statement.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Chemotaxis:", "options": [ "is directly preceded by tethering and rolling of white blood cells (WBCs) inside blood vessels.", "is directly preceded by margination of white blood cells (WBCs).", "is directly followed by emigration/diapedesis.", "is the ability of white blood cells (WBCs) to move down their own concentration gradient in response to chemical factors.", "is directly followed by recognition of non-self by white blood cells (WBCs)." ], "a": 4, "e": "Sequence: margination/rolling -> firm adhesion -> diapedesis -> chemotaxis -> recognition/phagocytosis. So chemotaxis is directly followed by recognition of non-self. Opt3 is wrong: chemotaxis is movement UP a chemoattractant gradient, not down WBC's own gradient.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "Thrombin is a key enzyme in the process of blood coagulation. Which one of the following is a role of thrombin?", "options": [ "Conversion of plasminogen into plasmin", "Hemolysis", "Activation of platelets", "Opsonization", "Fibrinolysis" ], "a": 2, "e": "Thrombin activates platelets (and factor V, factor XIII, fibrinogen->fibrin). Plasmin, not thrombin, converts plasminogen and drives fibrinolysis; opsonization and hemolysis are unrelated to thrombin.", "_mod": "blood", "src": "course", "exam": "mid1-paper" }, { "q": "The stretch reflex in the leg is evoked by striking the patellar tendon. The strike on the patellar tendon results in the direct (monosynaptic) excitation of an efferent neuron that synapses onto the __________, and also involves __________.", "options": [ "quadriceps muscle; direct (monosynaptic) inhibition of the efferent neuron that synapses onto the hamstrings muscles", "quadriceps muscle; activation of the hamstrings muscle", "hamstrings muscles; disynaptic inhibition (via an inhibitory interneuron) of the efferent neuron that synapses onto the quadriceps muscle", "quadriceps muscle; disynaptic inhibition (via an inhibitory interneuron) of the efferent neuron that synapses onto the hamstrings muscles", "patellar tendon; activation of the hamstrings muscle" ], "a": 3, "e": "Patellar tendon strike stretches quadriceps; Ia afferent monosynaptically excites the alpha motor neuron to the quadriceps (agonist), and via a disynaptic Ia inhibitory interneuron reciprocally inhibits the motor neuron to the antagonist hamstrings.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements is NOT CORRECT? Voltage-gated Na+ channels are:", "options": [ "located in the membrane of both neurons and muscle cells.", "involved in the depolarizing phase of the neuronal action potential.", "clustered at the axon hillock.", "clustered at nodes of Ranvier.", "most abundant on the dendrites." ], "a": 4, "e": "NOT-correct stem. Voltage-gated Na+ channels are in neurons and muscle, drive AP depolarization, and are clustered/high-density at the axon hillock and nodes of Ranvier. They are NOT most abundant on dendrites (hillock has highest density), so E is the false statement.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "The dihydropyridine (DHP) receptor in skeletal muscle:", "options": [ "acts as a Ca2+ sensor, opening when levels of Ca2+ outside the muscle cell increase.", "is found in the membrane of the sarcoplasmic reticulum.", "acts as a voltage-sensor which is physically coupled via a foot process to the ryanodine receptor.", "opens to allow Na+ to enter the cell during an action potential.", "pumps Ca2+ from the cytoplasm back into the sarcoplasmic reticulum." ], "a": 2, "e": "The DHP receptor is a modified voltage-sensitive Ca2+ channel in the T-tubule that acts as a voltage sensor; its foot process physically couples to the ryanodine receptor on the SR, mechanically opening it to release Ca2+. It does not sense external Ca2+ or pump Ca2+.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "The pair of descriptors which correctly describes directly-gated chemical synaptic transmission is:", "options": [ "receptor and effector are different molecules; effects are long lasting", "bidirectional communication; effects are fast in onset", "excitation travels from pre-synaptic to post-synaptic cell; gap junctions", "receptor and effector are the same molecule; effects are fast in onset", "excitation travels from post-synaptic to pre-synaptic cell; fast transmission" ], "a": 3, "e": "Directly-gated (ionotropic) transmission: the receptor IS the ion channel, so receptor and effector are the same molecule, and effects are fast in onset. Long-lasting effects and second messengers describe metabotropic (indirectly gated) transmission.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following nerve fibers transmits action potentials the slowest?", "options": [ "Large diameter unmyelinated fibers", "Small diameter myelinated fibers", "Large diameter myelinated fibers", "Small diameter unmyelinated fibers", "All fibers transmit action potentials at the same speed" ], "a": 3, "e": "Conduction velocity rises with fiber diameter and myelination. Slowest are small-diameter unmyelinated fibers (~0.5 m/s); fastest are large-diameter myelinated fibers (~100 m/s).", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "At the neuromuscular junction:", "options": [ "each muscle fiber is innervated by multiple presynaptic axons.", "the inhibitory neurotransmitter GABA is released from the motor neuron to inhibit muscle contraction.", "acetylcholine binds to voltage-gated Na+ channels.", "summation is required to generate muscle contraction.", "directly-gated chemical synaptic transmission occurs." ], "a": 4, "e": "At the NMJ, ACh binds ionotropic nicotinic receptors (the receptor IS the channel), i.e. directly-gated chemical transmission. Each fiber is innervated by one axon, ACh (not GABA) is the transmitter, one EPP suffices (no summation needed), so only E is correct.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "The duration of the absolute refractory period is dictated by:", "options": [ "inactivation of K+ leak channels.", "inactivation of Na+ leak channels.", "prolonged opening of voltage-gated Na+ channels.", "inactivation of voltage-gated Na+ channels.", "prolonged opening of voltage-gated K+ channels." ], "a": 3, "e": "The absolute refractory period lasts while voltage-gated Na+ channels are open or inactivated; their inactivation gate must be removed by repolarization before they can reopen, so its duration is dictated by inactivation of voltage-gated Na+ channels.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "An inhibitory pre-synaptic neuron releases the neurotransmitter __________ which binds to receptors on the post-synaptic membrane, opening __________ channels. Movement of the ion through its channel results in __________ of the post-synaptic neuron.", "options": [ "glycine; Na+; hyperpolarization", "glutamate; Cl-; hyperpolarization", "glycine; Cl-; hyperpolarization", "glutamate; Na+; depolarization", "GABA; K+; depolarization" ], "a": 2, "e": "Glycine is the major inhibitory neurotransmitter from spinal cord/brainstem interneurons; it binds ionotropic receptors that allow Cl- to enter, hyperpolarizing the postsynaptic cell. So: glycine; Cl-; hyperpolarization.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following is NOT a characteristic of white muscle fibers?", "options": [ "They fatigue rapidly.", "Cross-bridge cycling occurs rapidly resulting in fast contractions.", "They have numerous mitochondria to produce ATP.", "They have large numbers of myofilaments.", "They have a high glycogen content." ], "a": 2, "e": "White muscle = fast-glycolytic fibers, which have FEW mitochondria (rely on glycolysis/glycogen, fatigue fast, rapid cross-bridge cycling, many myofilaments). 'Numerous mitochondria' describes oxidative/red fibers, so it is NOT a characteristic.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following processes DOES NOT require adenosine triphosphate (ATP)?", "options": [ "Energizing the power stroke of the myosin cross-bridge", "Pumping Ca2+ ions back into the sarcoplasmic reticulum", "Movement of ions by the Na+/K+ pump", "Opening of ligand-gated ion channels", "Removal of the cross-bridge from its actin binding site during cross-bridge cycling" ], "a": 3, "e": "Power stroke, SERCA Ca2+ pump, and Na+/K+ pump all consume ATP; ATP binding also detaches the cross-bridge (absence causes rigor mortis). Ligand-gated ion channels open passively on ligand binding and require NO ATP.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "A key determinant of the resting membrane potential of a neuron is the __________ in the cell membrane.", "options": [ "total number of voltage-gated K+ channels", "total number of voltage-gated Na+ channels", "relative number of Na+ and K+ leak channels", "total number of ligand-gated ion channels that are activated by glutamate", "total number of ligand-gated ion channels that are activated by glycine" ], "a": 2, "e": "Resting potential is set by passive ion movement through nongated leak channels; its magnitude depends on the relative permeability/number of Na+ vs K+ leak channels (more K+ leak than Na+ leak). Voltage-/ligand-gated channels are closed at rest.", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following statements is NOT a property of afferent neurons?", "options": [ "They comprise part of the mixed peripheral nerve.", "The larger the diameter the faster they conduct action potentials.", "They carry sensory information to the central nervous system (CNS).", "They can be activated by the flow of ions through specialized receptors.", "They can make direct (monosynaptic) synapses onto muscle." ], "a": 4, "e": "Afferent neurons carry sensory info INTO the CNS, are part of mixed peripheral nerves, conduct faster with larger diameter, and are activated by ion flow through receptors. They synapse onto efferent/interneurons in the CNS, NOT directly onto muscle (that is the efferent neuron).", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which of the following statements is NOT CORRECT?", "options": [ "Electrotonic conduction spreads in one direction only due to the refractory period.", "Spatial summation is a process when post-synaptic potentials from a single pre-synaptic axon overlap in time and add together.", "Schwann cells produce myelin in the peripheral nervous system.", "Saltatory conduction occurs in myelinated nerve fibers.", "Both spatial and temporal summation occur simultaneously in the brain." ], "a": 1, "e": "Spatial summation is PSPs arriving together at DIFFERENT synapses (different presynaptic axons). PSPs from a single presynaptic axon overlapping in time is TEMPORAL summation, so this statement is NOT correct. (Other options A,C,D,E are all true.)", "_mod": "nms", "src": "course", "exam": "mid1-paper" }, { "q": "Which one of the following statements is CORRECT?", "options": [ "Post-synaptic potentials are all-or-none in amplitude.", "Post-synaptic potentials are always initiated at the axon Hillock.", "Excitatory post-synaptic potentials (EPSPs) decrease in amplitude as they travel.", "Action potentials are variable-strength signals that are transmitted over short distances only.", "Action potentials may be transmitted in either direction along an axon, towards the axon terminals or towards the dendrites." ], "a": 2, "e": "PSPs are graded synaptic potentials conducted decrementally, so EPSPs decrease in amplitude as they travel (TRUE). PSPs are not all-or-none, are initiated at synapses (not always the hillock), and APs are all-or-none, long-distance, and unidirectional due to refractoriness.", "_mod": "nms", "src": "course", "exam": "mid1-paper" } ] }, "feb-practice": { "id": "feb-practice", "name": "February Practice Quiz", "mins": 60, "hue": 70, "cover": [ "gi", "resp" ], "desc": "Official practice quiz (60 Q): Gastrointestinal and Respiratory physiology.", "questions": [ { "q": "Which of the following statements about CCK is accurate? (1) CCK is classified as a peptide hormone. (2) Acid entering the small intestine is the primary trigger for CCK release. (3) Fat and protein in the small intestine strongly stimulate CCK secretion. (4) CCK is produced by endocrine cells of the pancreas.", "options": [ "2, 4", "1, 4", "2, 3", "1, 2", "1, 3" ], "a": 4, "e": "Statements (1) & (3) are true: CCK is a peptide hormone (Table 15.2) and fat/protein (fatty acids+amino acids) in the small intestine strongly stimulate its release. Acid triggers secretin, not CCK; CCK is made by intestinal enteroendocrine cells, not the pancreas. So 1,3.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about segmentation is not correct?", "options": [ "Segmentation is important for the mixing of food with digestive enzymes.", "Segmentation is the main driving force moving food through the gastrointestinal tract.", "Segmentation slows the transit time to allow for the absorption of nutrients and water.", "There is little net movement of food during these contractions.", "Segmentation mostly occurs in the small intestine." ], "a": 1, "e": "NOT correct: segmentation is not the main propulsive force. Segmentation mixes chyme with 'little apparent net movement'; peristalsis/MMC propels food. The other statements (mixing, slows transit, little net movement, occurs in small intestine) are all true.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following regarding food intake is correct?", "options": [ "Ghrelin is an orexigenic factor.", "Factors which decrease food intake are called orexigenic factors.", "Insulin is an orexigenic factor.", "Factors which increase food intake are called anorexigenic factors.", "Leptin is an orexigenic factor." ], "a": 0, "e": "Ghrelin is orexigenic (increases food intake/hunger). Orexigenic factors increase intake; anorexigenic factors decrease it. Insulin and leptin are anorexigenic (decrease intake). The remaining options swap these definitions or misclassify, so only ghrelin is correct.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which is the most important factor regulating thirst under physiological conditions?", "options": [ "Dry mouth", "Dry throat", "All factors have the same effect on thirst.", "Plasma volume", "Plasma osmolality" ], "a": 4, "e": "Plasma osmolality is the most important physiological stimulus for thirst. Vander states explicitly: 'Plasma osmolarity is the most important stimulus under normal physiological conditions.' Plasma volume (baroreceptor) input is secondary; dry mouth/throat are minor.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The final formed saliva is:", "options": [ "hypotonic and acidic.", "isotonic and acidic.", "hypertonic and alkaline.", "hypotonic and alkaline.", "isotonic and alkaline." ], "a": 3, "e": "Final saliva is hypotonic and alkaline. Duct cells reabsorb Na+/Cl- and secrete K+/HCO3- while being water-impermeable, so saliva ends hypotonic; HCO3- makes it alkaline (buffers acid). Vander notes saliva contains HCO3- to neutralize acid.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following correctly describes ductal cells of the salivary glands?", "options": [ "They are important for protein, electrolyte and water secretion.", "They have tight junctions which allow the passage of water.", "They contract to push the saliva from the acinus to the striated duct.", "They add proteins to the saliva by exocytosis.", "They form the final alkaline hypotonic saliva." ], "a": 4, "e": "Salivary ductal cells form the final alkaline, hypotonic saliva: they reabsorb Na+/Cl-, secrete K+/HCO3-, and have tight junctions impermeable to water. Acinar cells (not duct cells) add protein by exocytosis and secrete the initial isotonic fluid.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Starch digestion begins in the ____________ with the addition of amylase.", "options": [ "Large intestine", "Esophagus", "Small intestine", "Mouth", "Stomach" ], "a": 3, "e": "Starch digestion begins in the mouth: salivary amylase initiates polysaccharide digestion. Vander: 'The digestion of starch by salivary amylase begins in the mouth.' It continues briefly in the stomach then by pancreatic amylase in the small intestine.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following is not a function of HCl in the stomach?", "options": [ "Partially digests macromolecules in food", "Sterilizes food", "All of these are functions of HCl.", "Dissolves food", "Activates pepsinogen to pepsin" ], "a": 2, "e": "'All of these are functions of HCl.' HCl partially digests/denatures protein macromolecules, kills bacteria (sterilizes), helps dissolve food, and activates pepsinogen to pepsin. All four listed roles are genuine HCl functions.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following inhibit HCl production by the stomach?", "options": [ "Histamine", "Intrinsic factor", "Vitamin B12", "Somatostatin", "Gastrin" ], "a": 3, "e": "Somatostatin inhibits HCl production. Vander: 'somatostatin—another paracrine substance—inhibits acid secretion.' Histamine and gastrin stimulate acid; intrinsic factor and B12 are unrelated to acid output regulation.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about pepsin is correct? (1) Pepsin is secreted as the inactive precursor pepsinogen. (2) Pepsin is secreted as an active enzyme. (3) Pepsinogen is activated by alkaline pH in the stomach lumen. (4) Pepsinogen is activated by HCl in the stomach.", "options": [ "1, 3", "2, 4", "1, 2", "2, 3", "1, 4" ], "a": 4, "e": "Statements (1) & (4) are true: pepsin is secreted as the inactive precursor pepsinogen, which is activated by HCl (low luminal pH), not alkaline pH. So 1,4. Statements (2) active enzyme and (3) alkaline activation are false.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The pancreatic acinar cells:", "options": [ "synthesize and secrete digestive enzymes.", "secrete water.", "secrete hydrochloric acid (HCl).", "secrete bicarbonate.", "synthesize and secrete intrinsic factor." ], "a": 0, "e": "Pancreatic acinar cells synthesize and secrete digestive enzymes; duct cells secrete HCO3- and water. HCl is gastric (parietal cells); intrinsic factor is gastric.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about pancreatic enzymes is correct?", "options": [ "Pancreatic lipase is responsible for carbohydrate digestion.", "All pancreatic enzymes are secreted in active form.", "Trypsinogen is activated by enterokinase in the duodenum.", "Pancreatic enzymes are not essential for life.", "Pancreatic amylase digests triglycerides." ], "a": 2, "e": "Trypsinogen is activated by enterokinase (enteropeptidase) on the duodenal brush border, forming trypsin. Proteases are secreted as zymogens (not all active); lipase digests fat, amylase carbs; pancreatic enzymes are essential.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The hepatic artery brings _____________ blood to the liver while the hepatic vein brings ______________ to the liver.", "options": [ "oxygen poor and nutrient rich; oxygen rich and nutrient poor", "oxygen rich and nutrient rich; oxygen poor and nutrient poor", "oxygen poor and nutrient poor; oxygen rich and nutrient rich", "oxygen poor and nutrient rich; oxygen poor and nutrient rich", "oxygen rich and nutrient poor; oxygen poor and nutrient rich" ], "a": 4, "e": "Hepatic artery delivers oxygen-rich, nutrient-poor blood; the venous (hepatic portal) supply is oxygen-poor but nutrient-rich. Option E captures this dual supply. (Stem loosely says 'hepatic vein,' but intended physiology = the portal/venous inflow.)", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about bile acids is not correct? They are:", "options": [ "recycled back into the ileum of the small intestine.", "taken up from the intestinal lumen into enterocytes by a primary active transport pathway.", "synthesized by hepatocytes.", "released from hepatocytes into the canalicular networks by a primary active transport pathway.", "secreted into the duodenum or stored in the gall bladder." ], "a": 1, "e": "FALSE statement: bile salts are reabsorbed from the lumen by Na+-coupled SECONDARY active transport in the ileum, not primary active transport. The other choices (recycled to ileum, hepatocyte synthesis, canalicular primary active secretion, duodenum/gallbladder) are true.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about gastrin is not correct? Gastrin:", "options": [ "is secreted by chief cells.", "stimulates GI motility.", "is secreted by G-cells.", "is a hormone.", "stimulates hydrochloric acid secretion by the parietal cell." ], "a": 0, "e": "FALSE statement: gastrin is secreted by G cells, NOT chief cells (chief cells secrete pepsinogen). Gastrin is a hormone that stimulates parietal-cell HCl secretion and GI motility.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which one of the following inhibits HCl production?", "options": [ "CCK", "Acetylcholine", "Histamine", "Somatostatin", "Gastrin" ], "a": 3, "e": "Somatostatin (from D cells) inhibits HCl secretion, acting on parietal cells and inhibiting gastrin/histamine release. Gastrin, ACh, and histamine all stimulate acid; CCK is not an inhibitor of parietal cells here.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Mixing movements:", "options": [ "primarily propel food forward along the gastrointestinal tract.", "are the main mechanism of nutrient absorption.", "take place only in the stomach.", "occur only during fasting.", "promote digestion by mixing food with digestive secretions." ], "a": 4, "e": "Mixing (segmentation) movements promote digestion by mixing food with digestive secretions, with little net forward movement. Peristalsis (not mixing) propels; absorption is via villi; mixing occurs mainly in small intestine, not just stomach, and during meals.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Regarding the phases of gastric secretions:", "options": [ "The cephalic phase is initiated when food reaches your stomach.", "The intestinal phase is a stimulatory phase.", "The gastric phase is an inhibitory phase.", "The intestinal phase is mediated by gastrin.", "The cephalic phase is initiated by the sight, smell, taste of food." ], "a": 4, "e": "The cephalic phase is initiated by sight, smell, taste (and chewing) of food. It begins BEFORE food reaches the stomach; the intestinal phase is primarily inhibitory (enterogastrones) and not gastrin-mediated; the gastric phase is stimulatory.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about fat digestion and absorption in the small intestine is correct?", "options": [ "Triglycerides are broken down into amino acids before absorption.", "Chylomicrons are absorbed into the enterocyte nucleus.", "Bile acids and phospholipids help emulsify lipid droplets, aiding pancreatic lipase action.", "Micelles are formed in the stomach to transport fats.", "Fatty acids and monoglycerides are absorbed directly into blood capillaries from the intestinal lumen." ], "a": 2, "e": "Bile salts and phospholipids emulsify large lipid droplets, increasing surface area for pancreatic lipase. Triglycerides yield fatty acids+monoglycerides (not amino acids); chylomicrons enter lacteals (not the nucleus/blood); micelles form in the small intestine, not the stomach.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The large intestine has:", "options": [ "villi and crypts", "villi only.", "a greater surface area than the small intestine.", "crypts only.", "neither villi nor crypts." ], "a": 3, "e": "The large intestine mucosa lacks villi but contains crypts (intestinal glands/crypts of Lieberkuhn) -> 'crypts only.' Its surface area is much SMALLER than the small intestine despite a larger diameter.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following enters the duodenum first during normal digestion?", "options": [ "Bile", "Pancreatic secretions", "Gastric chyme", "Saliva", "Lymph" ], "a": 2, "e": "Gastric chyme enters the duodenum first. Acid/fat/protein in the chyme then trigger secretin and CCK, which stimulate pancreatic secretions and gallbladder contraction (bile). So chyme arrives before pancreatic/bile secretions; saliva and lymph do not enter the duodenum.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements regarding the large intestine is correct?", "options": [ "The basic electrical rhythm of the large intestine is faster than the small intestine.", "The large intestine absorbs more water than the small intestine.", "The large intestine has more absorptive capacity than the small intestine.", "The final stages of carbohydrate and protein digestion occur in the large intestine.", "The secretion of water by the large intestine depends on chloride gradients." ], "a": 4, "e": "Large intestine secretes HCO3- into the lumen coupled to Cl- absorption; its fluid secretion depends on chloride gradients. False options: colon BER is slower than SI; SI absorbs far more water (80% of 8000 mL) and has greater absorptive capacity; final CHO/protein digestion is in the SI.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The parietal cells of the stomach secrete:", "options": [ "Pepsinogen", "Somatostatin", "Hydrochloric acid (HCl)", "Gastrin", "Acetylcholine" ], "a": 2, "e": "Parietal cells secrete hydrochloric acid (and intrinsic factor). Pepsinogen is from chief cells, gastrin from G cells, somatostatin from D cells, and acetylcholine is a neurotransmitter, not a parietal-cell secretion.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements concerning the large intestine is correct?", "options": [ "The large intestine has as much absorptive capacity as the small intestine.", "The final stages of carbohydrate and protein digestion occur in the colon.", "None of the answers are correct.", "Large intestine movements are slower than those in the small intestine.", "All of the answers are correct." ], "a": 3, "e": "Large intestine movements (haustral churning/mass movements) are slower than small-intestine motility. The colon does NOT have as much absorptive capacity as the SI, and final carbohydrate/protein digestion occurs in the SI, not the colon, so 'none/all correct' fail.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about the pancreas are correct? (1) The pancreas produces only endocrine secretions. (2) The pancreas produces enzymes that are secreted into the gastrointestinal tract. (3) The pancreas secretes bicarbonate into the duodenum for acid neutralization so that pancreatic enzymes may be functional. (4) The endocrine portion of the pancreas secretes digestive enzymes.", "options": [ "2, 4", "1, 2", "1, 4", "1, 3", "2, 3" ], "a": 4, "e": "Vander's 16e Ch15: pancreas has BOTH endocrine & exocrine functions (so #1 false). Exocrine portion secretes HCO3- + digestive enzymes into duodenum; acid would inactivate enzymes if not neutralized (so #2, #3 true). Endocrine portion secretes insulin/glucagon, NOT enzymes (so #4 false). True=2,3 -> option index 4.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "The correct order of layering in the digestive tract wall, from deep to superficial, is:", "options": [ "mucosa, muscularis, submucosa, serosa", "serosa, mucosa, submucosa, muscularis", "mucosa, submucosa, muscularis, serosa", "muscularis, mucosa, serosa, submucosa", "submucosa, mucosa, muscularis, serosa" ], "a": 2, "e": "From deep (lumen) to superficial: mucosa, then submucosa, then muscularis (externa), then serosa. The text describes lumen->mucosa (epithelium/lamina propria/muscularis mucosa)->submucosa->muscularis externa->serosa.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following is absorbed by the lymphatic system (lacteals) rather than directly into the blood in the small intestine?", "options": [ "Iron", "Amino acids", "Glucose", "Water", "Chylomicrons" ], "a": 4, "e": "Chylomicrons are too large to cross the capillary basement membrane and instead enter lacteals (lymphatic vessels in the villi). Iron, amino acids, glucose, and water are absorbed directly into blood capillaries.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "What is the primary function of the enteric nervous system?", "options": [ "Absorption of nutrients", "Production of digestive enzymes", "Voluntary control of swallowing", "Filtration of blood", "Regulation of smooth muscle contraction and secretion in the GIT" ], "a": 4, "e": "The enteric nervous system (myenteric + submucosal plexuses) is the GI tract's intrinsic neural control, regulating smooth muscle contraction (motility) and exocrine gland secretion. It does not itself absorb nutrients, make enzymes, control voluntary swallowing, or filter blood.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which hormone is released in response to acid entering the duodenum and stimulates pancreatic bicarbonate secretion?", "options": [ "Gastrin", "Cholecystokinin (CCK)", "Peptide YY", "Insulin", "Secretin" ], "a": 4, "e": "Secretin is released from small-intestine enteroendocrine (S) cells in response to acid entering the duodenum and is the primary stimulant of pancreatic HCO3- secretion to neutralize the acid. CCK responds to fat/protein and drives enzyme secretion.", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Secretin:", "options": [ "is produced by I-cells in the duodenum and jejunum.", "stimulates HCl secretion in the stomach.", "increases gastric motility to speed stomach emptying.", "is released primarily in response to fat and protein in the duodenum.", "inhibits gastrin secretion." ], "a": 4, "e": "Secretin is an enterogastrone that inhibits gastrin/gastric acid secretion. False options: it is from S-cells (I-cells make CCK); it inhibits (not stimulates) HCl; it inhibits (not increases) gastric motility; its primary stimulus is acid, not fat/protein (which triggers CCK).", "_mod": "gi", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following is NOT a function of the respiratory system?", "options": [ "Synthesizes erythropoietin", "Provides oxygen and eliminates carbon dioxide", "Contributes to olfaction", "Protects against microbial infection", "Regulates blood pH" ], "a": 0, "e": "Vander Table 13.1 lists respiratory functions: O2/CO2 exchange, pH regulation, phonation, defense vs microbes, olfaction, processing chemical messengers. Erythropoietin is secreted by the KIDNEYS, not the lungs, so it is NOT a respiratory function.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "What is the fundamental unit of the respiratory system where gas exchange occurs?", "options": [ "Bronchi", "Larynx", "Pharynx", "Alveoli", "Trachea" ], "a": 3, "e": "The alveoli are the functional units / sites of gas exchange with the blood. Bronchi, larynx, pharynx, and trachea are conducting passages, not gas-exchange sites.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "What is the main muscle responsible for inspiration during quiet breathing?", "options": [ "Internal intercostals", "Parasternal intercostals", "Abdominal muscles", "Diaphragm", "External intercostals" ], "a": 3, "e": "The diaphragm is the most important inspiratory muscle during normal quiet breathing; external intercostals assist. Internal intercostals/abdominals are expiratory (active expiration).", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which law states that the pressure and volume of a gas are inversely proportional at constant temperature?", "options": [ "Boyle's law", "LaPlace's law", "Fick's law", "Dalton's law", "Henry's law" ], "a": 0, "e": "Boyle's law: at constant temperature the pressure and volume of a gas are inversely proportional (P1V1=P2V2).", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following conditions is associated with increased lung compliance?", "options": [ "Asthma", "Emphysema", "Pulmonary fibrosis", "Bronchitis", "Pneumonia" ], "a": 1, "e": "Emphysema destroys elastic tissue, raising lung compliance ('emphysema (increased compliance)'). Fibrosis, asthma, bronchitis, and pneumonia stiffen the lung / lower compliance.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about airflow is correct?", "options": [ "Air moves via the process of osmosis", "Expiration occurs when Palveolar is greater than Patmospheric", "Inspiration occurs when Palveolar is greater than Patmospheric", "Air moves from a region of low pressure to a region of high pressure", "Expiration occurs when Patmospheric is greater than Palveolar" ], "a": 1, "e": "Air flows by bulk flow down a pressure gradient (high to low). Expiration occurs when Palv > Patm (air pushed out); inspiration when Palv < Patm. Only the Palv>Patm=expiration statement is correct.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which pressure is the force responsible for keeping the alveoli open:", "options": [ "Atmospheric pressure (PATM)", "Intrapleural pressure (PIP)", "Transpulmonary pressure (PTP)", "Alveolar pressure (PALV)", "Mean arterial pressure (MAP)" ], "a": 2, "e": "The lungs/alveoli are held open by the positive transpulmonary pressure (Ptp = Palv - Pip), which opposes elastic recoil. Pip is subatmospheric; Ptp is the distending pressure.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The total/minute ventilation is obtained by multiplying the _____________ by the respiratory frequency.", "options": [ "tidal volume", "inspiratory capacity", "reserve volume", "vital capacity", "total lung capacity" ], "a": 0, "e": "Minute (total) ventilation = tidal volume x respiratory rate (frequency).", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "During normal, relaxed respiration, about 500 mL of air enters and leaves the lungs with each respiratory cycle. This is called the:", "options": [ "expiratory reserve volume", "total lung capacity", "tidal volume", "vital capacity", "inspiratory reserve volume" ], "a": 2, "e": "The ~500 mL of air moved in/out per breath during quiet (relaxed) breathing is the tidal volume.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Within the respiratory tract, the trachea leads directly to the:", "options": [ "terminal bronchioles.", "respiratory bronchioles.", "primary bronchi.", "alveolar sacs.", "alveolar ducts." ], "a": 2, "e": "The trachea branches directly into the two primary (main) bronchi, one per lung. Bronchioles, terminal/respiratory bronchioles, alveolar ducts and sacs are downstream generations.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following statements about respiratory bronchioles is correct? (1) They are found in the conducting zone. (2) They have occasional alveoli. (3) They are the smallest airways without alveoli. (4) They are found in the respiratory zone.", "options": [ "1, 4", "3, 4", "1, 3", "1, 2", "2, 4" ], "a": 4, "e": "Respiratory bronchioles mark the start of the respiratory zone (stmt 4) and bear occasional/scattered alveoli (stmt 2). Stmt 1 (conducting zone) and stmt 3 (smallest WITHOUT alveoli = terminal bronchioles) are false. True = 2,4.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The conducting zone of the respiratory system includes all of the following passages except the:", "options": [ "All of the regions are part of the conducting zone.", "trachea.", "alveolar sacs.", "terminal bronchioles.", "bronchi." ], "a": 2, "e": "Conducting zone runs from trachea to terminal bronchioles and has no alveoli; it includes trachea, bronchi, terminal bronchioles. Alveolar sacs are pure alveoli in the respiratory zone, so they are the exception.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "____________ describes how fluid flow through a tube is affected by viscosity, tube length, and especially radius.", "options": [ "Boyle's Law", "Poiseuille's law", "Dalton's law", "Henry's Law", "LaPlace's law" ], "a": 1, "e": "Poiseuille's law relates flow through a tube to pressure gradient, fluid viscosity, tube length, and the fourth power of the radius (radius is the dominant factor).", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "____________ states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressure of the individual gases.", "options": [ "Henry's law", "Poiseuille's law", "LaPlace's law", "Boyle's law", "Dalton's law" ], "a": 4, "e": "Dalton's law: in a mixture of non-reacting gases, total pressure equals the sum of the partial pressures of the individual gases.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Type II alveolar cells function in reducing surface tension by producing and secreting:", "options": [ "adrenaline.", "human growth hormone.", "surfactant.", "All of these options are correct.", "water." ], "a": 2, "e": "Type II alveolar cells synthesize and secrete surfactant, a detergent-like phospholipid-protein mixture that lowers surface tension and prevents alveolar collapse.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following correctly describes the pulmonary circulatory system? It:", "options": [ "is concerned with the exchange of oxygen between the blood and the peripheral tissues.", "has arterioles with thick walls and much smooth muscle.", "is a high pressure system.", "is a high resistance system.", "has high compliance vessels." ], "a": 4, "e": "Pulmonary circulation is a low-pressure, low-resistance system with thin-walled, distensible (high-compliance) vessels and little smooth muscle. It exchanges gas in the lungs, not peripheral tissues. Correct = high compliance vessels.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "What does a right shift in the oxygen dissociation curve indicate about the binding of oxygen to hemoglobin?", "options": [ "Decreased carbon dioxide loading", "Increased oxygen unloading", "Increased binding of hydrogen ions", "No overall change", "Decreased oxygen unloading" ], "a": 1, "e": "A rightward shift of the O2-Hb dissociation curve reflects decreased Hb affinity for O2, so at any given PO2 less O2 is bound and more O2 is released (increased unloading) to tissues.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The function of lung surfactant compounds is to:", "options": [ "warm the air as it enters the alveoli.", "reduce surface tension of alveolar fluid.", "keep the lungs moist so gas diffusion can occur.", "reduce transpulmonary pressure.", "filter impurities from the inspired air." ], "a": 1, "e": "Surfactant's function is to reduce the surface tension of the fluid layer lining the alveoli, increasing compliance and preventing alveolar collapse.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "This lung capacity is equal to the tidal volume plus inspiratory reserve volume plus expiratory reserve volume (TV + IRV + ERV):", "options": [ "Vital capacity (VC)", "Functional residual capacity (FRC)", "Reserve volume (RV)", "Inspiratory capacity (IC)", "Total lung capacity (TLC)" ], "a": 0, "e": "Vital capacity = TV + IRV + ERV, the maximal volume expired after a maximal inspiration. It excludes residual volume; TLC would add RV.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The amount of air remaining in the lungs after a maximal forceful expiration is the:", "options": [ "Vital capacity", "Tidal volume", "Inspiratory capacity", "Inspiratory reserve volume", "Residual volume" ], "a": 4, "e": "Residual volume is the air remaining in the lungs after a maximal forceful expiration (~1200 mL); the lungs are never fully emptied.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The central chemoreceptors will increase their firing rate in direct response to increases in the concentration of ____________ in the brain extracellular fluid, resulting in _____________ ventilation.", "options": [ "lactic acid; increase", "hydrogen ions; increase", "carbon dioxide; decrease", "hydrogen ions; decrease", "carbon dioxide; increase" ], "a": 1, "e": "Central chemoreceptors in the medulla are stimulated directly by increased H+ concentration in brain extracellular fluid (CO2 acts indirectly via H+), increasing ventilation.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "When bicarbonate (HCO3) diffuses out of the red blood cells into the plasma in systemic capillaries, ____ diffuses into the RBCs to replace it.", "options": [ "chloride ion (Cl-)", "O2", "hydrogen ion (H+)", "hydroxyl ion (OH-)", "CO2" ], "a": 0, "e": "In systemic (tissue) capillaries, HCO3- formed in RBCs exits into plasma in exchange for Cl- moving into the RBC (the chloride shift) to maintain electroneutrality.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The reaction of _____ + _____ produces carbonic acid (H2CO3), catalyzed by the enzyme ______________.", "options": [ "O2; H2O; carbonic anhydrase", "CO2; H2O; dehydrogenase", "CO2; H2O; carbonic anhydrase", "H+ + HCO3-; carbonic anhydrase", "H+ + HCO3-; dehydrogenase" ], "a": 2, "e": "CO2 + H2O combine to form carbonic acid (H2CO3), a reaction catalyzed by carbonic anhydrase in erythrocytes.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following apply to the transport of oxygen (O2) in blood? (1) Oxygen has a high solubility in plasma. (2) The majority of oxygen (> 98 %) is found dissolved in plasma. (3) The amount of oxygen dissolved in plasma is proportional to the PO2 and the solubility of oxygen in the blood. (4) The binding of oxygen to hemoglobin is a reversible process.", "options": [ "1, 3", "1, 4", "3, 4", "2, 3", "1, 2" ], "a": 2, "e": "True: (3) dissolved O2 is proportional to PO2 and solubility (Henry's law); (4) Hb-O2 binding is reversible. False: (1) O2 has LOW solubility; (2) >98% is on Hb, not dissolved.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The diffusion of oxygen from the alveoli into the blood of the alveolar capillaries is rapid and involves diffusion across the membrane of an __________ cell, then diffusion across the membrane of an _____________ cell.", "options": [ "endothelial, alveolar type II", "alveolar type I, endothelial", "endothelial, alveolar type I", "alveolar type II, endothelial", "alveolar type I, alveolar type II" ], "a": 1, "e": "O2 diffuses from alveolus across the type I alveolar (epithelial) cell membrane, then across the capillary endothelial cell membrane into blood.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The major automatic (involuntary) regulatory centers for respiration, especially the inspiratory centers, are located in the _________ region of the brain.", "options": [ "medulla", "None of these answers are correct", "spinal cord", "cerebral cortex", "pons" ], "a": 0, "e": "The automatic (involuntary) respiratory rhythm generator and inspiratory neurons (DRG) of the medullary respiratory center are located in the medulla oblongata.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "The major factor which normally affects regional blood flow in the lungs is:", "options": [ "the anatomical shunt.", "All of these options affect regional blood flow equally.", "ventilation.", "gravity.", "cardiac output." ], "a": 3, "e": "Gravity is the major factor determining regional blood-flow (perfusion) distribution in the lung, increasing filling of vessels at the lung base in upright posture.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "What is the main driving force for oxygen movement from alveoli into pulmonary capillaries?", "options": [ "Bulk flow", "Facilitated diffusion", "Osmosis", "Filtration", "Partial pressure gradient" ], "a": 4, "e": "O2 moves from alveoli into pulmonary capillary blood by diffusion driven by the partial pressure (PO2) gradient across the alveolar-capillary membrane.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "Which of the following best describes the role of hemoglobin in oxygen transport?", "options": [ "It transports carbon dioxide only", "It increases blood viscosity", "It produces surfactant", "It dissolves oxygen in plasma", "It binds oxygen reversibly" ], "a": 4, "e": "Hemoglobin's role is to bind oxygen reversibly, carrying >98% of blood O2; it loads in lungs and unloads in tissues.", "_mod": "resp", "src": "course", "exam": "feb-practice" }, { "q": "What is the primary mechanism by which carbon dioxide is transported in the blood?", "options": [ "As carbonic acid", "Bound to hemoglobin", "As bicarbonate ions", "Bound to platelets", "Dissolved in plasma" ], "a": 2, "e": "Most CO2 (about 60-65%) is transported as bicarbonate ions in plasma after conversion in erythrocytes; ~25-30% as carbamino-Hb and ~10% dissolved.", "_mod": "resp", "src": "course", "exam": "feb-practice" } ] }, "final-practice": { "id": "final-practice", "name": "Final Exam Practice", "mins": 165, "hue": 278, "cover": [ "renal", "endo", "repro" ], "desc": "Official final practice exam (96 Q): Renal, Endocrine and Reproductive physiology.", "questions": [ { "q": "Which of the following statements about water reabsorption is correct? (1) Water reabsorption is primarily dependent on K+. (2) Water reabsorption in the cortical and medullary collecting ducts is regulated by anti-diuretic hormone (ADH). (3) Water reabsorption in the loop of Henle is under hormonal control. (4) The greatest amount of water reabsorption is in the proximal tubule.", "options": [ "2, 3", "1, 2", "2, 4", "1, 3", "1, 4" ], "a": 2, "e": "Statements 2 (ADH regulates water reabsorption in cortical+medullary collecting ducts) and 4 (greatest water reabsorption, ~two-thirds, is in the proximal tubule) are true. Loop of Henle is not under hormonal control (3 false); reabsorption follows Na+, not K+ (1 false). Answer: '2, 4'.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Water permeability is:", "options": [ "low in the collecting duct when ADH is present.", "high in the distal convoluted tubule.", "high in the proximal tubule.", "low in the descending limb of Henle's loop.", "high in the ascending limb of Henle's loop." ], "a": 2, "e": "The proximal tubule is highly permeable to water (reabsorbs ~two-thirds of filtered water). The ascending limb is impermeable; DCT and collecting duct permeability depends on ADH (low without it); the descending limb is highly permeable. Best answer: high in the proximal tubule.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following substances secreted by the kidneys is a hormone?", "options": [ "Creatine", "Bilirubin", "Uric acid", "Renin", "Urea" ], "a": 3, "e": "Of the listed kidney-secreted substances, renin is the one that functions as a hormonal/regulatory signal (renin-angiotensin system). Creatine, bilirubin, uric acid, and urea are metabolic/waste products, not hormones. Answer: Renin.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following is not a function of the kidneys?", "options": [ "Synthesizing EPO", "Regulation of extracellular fluid volume", "Regulation of inorganic ion composition", "Synthesizing glucose", "Synthesizing aldosterone" ], "a": 4, "e": "Kidneys synthesize EPO, regulate ECF volume and inorganic ion composition, and perform gluconeogenesis (synthesize glucose). They do NOT synthesize aldosterone, which is made by the adrenal cortex. Answer: Synthesizing aldosterone.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following statements about atrial natriuretic peptide (ANP) is correct? (1) ANP is synthesized by the juxtaglomerular cells in the kidney. (2) ANP inhibits Na+ reabsorption. (3) ANP is released following atrial distension. (4) ANP promotes the actions of aldosterone.", "options": [ "1, 4", "1, 3", "2, 4", "1, 2", "2, 3" ], "a": 4, "e": "Statements 2 (ANP inhibits Na+ reabsorption) and 3 (ANP released following atrial distension) are true. ANP is made by atrial cells, not JG cells (1 false); it inhibits, not promotes, aldosterone (4 false). Answer: '2, 3'.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following statements about the renin-angiotensin system is correct?", "options": [ "Angiotensin II acts on the adrenal cortex to stimulate the release of aldosterone.", "Angiotensinogen is released from the juxtaglomerular cells in the kidney.", "Renin is synthesized and released from the liver.", "Angiotensinogen is the sensor for low Na+.", "Aldosterone increases Na+ secretion into the tubular lumen." ], "a": 0, "e": "Angiotensin II acts directly on the adrenal cortex to stimulate aldosterone secretion. Angiotensinogen is from the liver (not JG cells); renin is from kidney JG cells (not liver); aldosterone increases Na+ reabsorption (not secretion). Answer: option A.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Aldosterone is a _________________ hormone released from the ____________________.", "options": [ "steroid; kidney", "peptide; adrenal cortex", "steroid; liver", "peptide; liver", "steroid; adrenal cortex" ], "a": 4, "e": "Aldosterone is a steroid hormone synthesized and released by the adrenal cortex (zona glomerulosa). Answer: steroid; adrenal cortex.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Anti-diuretic hormone (ADH/vasopressin) is principally produced in the:", "options": [ "supraoptic nuclei in the hypothalamus", "anterior pituitary", "paraventricular nuclei in the hypothalamus", "suprachiasmatic nuclei in the hypothalamus", "posterior pituitary" ], "a": 0, "e": "ADH/vasopressin is principally produced by the supraoptic nucleus of the hypothalamus (SON predominantly makes vasopressin; PVN predominantly makes oxytocin). The posterior pituitary stores/releases it but does not synthesize it. Answer: supraoptic nuclei.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Anti-diuretic hormone (ADH/vasopressin):", "options": [ "is released in response to an increase in blood volume.", "decreases renal water reabsorption.", "is a steroid hormone.", "is released in response to an increase in blood osmolarity.", "is produced primarily by the PVN in the hypothalamus." ], "a": 3, "e": "ADH is released in response to increased blood osmolarity (hypothalamic osmoreceptors) and to decreased blood volume. It increases water reabsorption, is a peptide (not steroid), and is predominantly made by the SON (PVN is mainly oxytocin), so only option D is correct.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The segment of the nephron that is NOT permeable to water even in the presence of anti-diuretic hormone (ADH) is the:", "options": [ "Proximal tubule", "Descending limb of the loop of Henle", "Distal convoluted tubule", "Collecting duct", "Ascending limb of the loop of Henle" ], "a": 4, "e": "The ascending limb of the loop of Henle is impermeable to water even with ADH present (it reabsorbs solute without water, generating the medullary gradient). ADH affects collecting duct/DCT permeability; proximal tubule and descending limb are water-permeable. Answer: ascending limb.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The renal corpuscle is comprised of the glomerulus and _____________.", "options": [ "Loop of Henle", "Proximal convoluted tubule", "Distal convoluted tubule", "Bowman's space", "Vasa recta" ], "a": 3, "e": "Vander: 'The combination of a glomerulus and a Bowman's capsule constitutes a renal corpuscle.' Of the options, Bowman's space (within Bowman's capsule) is the corpuscle component; tubular segments and vasa recta are not.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The renal corpuscles of the juxtamedullary nephrons are located in the _____________ while the loop of Henle is mostly found in the ____________.", "options": [ "cortex; medulla", "medulla; medulla", "medulla; cortex", "cortex; cortex", "medulla; cortex and medulla" ], "a": 0, "e": "Vander: juxtamedullary nephrons' renal corpuscle 'lies in the part of the cortex closest to the cortical-medullary junction' and their loops of Henle 'plunge deep into the medulla.' So corpuscle in cortex; loop mostly in medulla.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Reabsorption is a renal process whereby solutes and water:", "options": [ "move from the peritubular capillaries back into the lumen of a tubule.", "move from the glomerular capillaries into Bowman's space.", "move from the lumen of a tubule into the peritubular capillaries.", "move from Bowman's space back into the glomerular capillaries.", "move from the interstitial space around the nephron back into the lumen of a tubule." ], "a": 2, "e": "Vander: 'When the direction of movement is from tubular lumen to peritubular capillary plasma, the process is called tubular reabsorption.' Thus solutes/water move from the tubule lumen into the peritubular capillaries.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Atrial natriuretic peptide (ANP) is released in response to ________ and acts to ________.", "options": [ "low Na+; retain water", "atrial distension; inhibit Na+ reabsorption", "low blood volume; raise aldosterone", "atrial contraction; increase renin", "ventricular stretch; activate angiotensin" ], "a": 1, "e": "Vander: ANP is secreted by cardiac atrial cells; 'the specific stimulus is increased atrial distension' and 'ANP acts on several tubular segments to inhibit Na+ reabsorption.' So atrial distension; inhibit Na+ reabsorption.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following statements about potassium (K+) handling by the kidneys is correct?", "options": [ "Hyperkalemia refers to abnormally low plasma potassium levels.", "All of the filtered K+ is excreted in the urine.", "Most filtered K+ is reabsorbed in the distal convoluted tubule.", "Antidiuretic hormone increases K+ secretion in the collecting duct.", "Regulation of urinary K+ levels occurs primarily in the cortical collecting duct." ], "a": 4, "e": "Vander: 'changes in K+ excretion are due mainly to changes in K+ secretion by [the cortical collecting ducts].' Regulation occurs primarily in the cortical collecting duct. Hyperkalemia=high; most filtered K+ is reabsorbed (proximally); aldosterone (not ADH) drives K+ secretion.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which statement correctly distinguishes cortical nephrons from juxtamedullary nephrons?", "options": [ "Juxtamedullary nephrons make up about 85% of all nephrons and perform only basic filtration functions.", "Cortical nephrons are associated with the vasa recta, while juxtamedullary nephrons are associated only with peritubular capillaries.", "Juxtamedullary nephrons lack a loop of Henle and are found exclusively in the renal pelvis.", "Cortical nephrons have long loops of Henle that extend deep into the medulla and primarily regulate urine concentration.", "Cortical nephrons are located mainly in the cortex and are primarily responsible for the basic renal processes of filtration, reabsorption, and secretion." ], "a": 4, "e": "Vander: 'The majority of nephrons are cortical...located in the outer cortex...involved in reabsorption and secretion.' ~15% are juxtamedullary (not 85%); cortical link to peritubular caps, juxtamedullary to vasa recta; juxtamedullary have long loops into medulla.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The components of the glomerular filtration membrane that the glomerular filtrate must pass through include:", "options": [ "Fenestrated capillary endothelium", "Basement membrane", "Podocytes with filtration slits and basement membrane", "Podocytes with filtration slits, basement membrane, and fenestrated capillary endothelium", "Podocytes with filtration slits" ], "a": 3, "e": "Vander: filtration barrier = three layers: fenestrated capillary endothelium, basement membrane, and podocyte epithelium with filtration slits. Filtrate must cross all three, so the complete set is the answer.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "In a healthy kidney, which of the following is readily filtered at the glomerulus?", "options": [ "All of the options listed are readily filtered", "Red blood cells", "Glucose and albumin", "Glucose", "Albumin" ], "a": 3, "e": "Vander: blood cells and plasma proteins (incl. albumin) are 'turned back'/not filtered; only low-MW solutes are freely filtered. Glucose is freely filtered. 'Glucose and albumin' is wrong because albumin is excluded.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Inulin:", "options": [ "is reabsorbed by the renal tubule.", "regulates the amount of glucose in the blood.", "is found naturally in the body.", "is secreted into the renal tubule.", "clearance can be used to measure the glomerular filtration rate (GFR)." ], "a": 4, "e": "Inulin is freely filtered but not reabsorbed, secreted, or metabolized, so its clearance equals GFR (UV/P). Vander: 'the GFR of a person is equal to the clearance of inulin.' It is found in plants, not made in the body, and does not regulate glucose.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Aldosterone promotes the reabsorption of sodium and the excretion of:", "options": [ "calcium", "bicarbonate", "magnesium", "potassium", "chloride" ], "a": 3, "e": "In the cortical collecting ducts aldosterone stimulates Na+ reabsorption and simultaneously enhances K+ secretion (excretion). So Na+ is reabsorbed and K+ (potassium) is excreted.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The plasma concentration at which a particular substance begins to appear in the urine is the:", "options": [ "filtered load.", "clearance.", "transport maximum (Tm).", "filtration fraction.", "renal threshold." ], "a": 4, "e": "The renal threshold is the plasma concentration at which a substance first appears in the urine (reabsorption saturated). Tm is the maximum transport rate, not a plasma concentration. Confirmed by Vander glucose threshold discussion and standard references.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The renal \"countercurrent\" mechanism is dependent upon the anatomic relationship between:", "options": [ "the loop of Henle and the vasa recta.", "the glomerulus and the distal tubule.", "the distal tubule and the macula densa.", "the glomerulus and the loop of Henle.", "the afferent and efferent arteriole and the loop of Henle." ], "a": 0, "e": "The countercurrent mechanism depends on the hairpin anatomy of the loop of Henle (countercurrent multiplier) acting with the parallel vasa recta (countercurrent exchanger) that preserves the medullary gradient.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which of the following statements regarding the nephron is correct?", "options": [ "The ascending limb of the loop of Henle is permeable to water.", "Water permeability in the loop of Henle is regulated by ADH (anti-diuretic hormone/vasopressin).", "Water permeability in the collecting duct is regulated by ADH (anti-diuretic hormone/vasopressin).", "The ascending limb of the loop of Henle is impermeable to NaCl.", "There is no water reabsorption in the descending limb of the loop of Henle." ], "a": 2, "e": "Only C is true: ADH regulates water permeability of the collecting duct. The ascending limb is impermeable to water but reabsorbs NaCl; the descending limb is water-permeable; ADH does not act on the loop of Henle.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The osmoreceptors that sense changes in plasma osmolarity are located in the:", "options": [ "Hypothalamus", "Glomerulus", "Carotid sinus", "Thalamus", "Afferent arteriole" ], "a": 0, "e": "The osmoreceptors that sense plasma osmolarity and control vasopressin secretion are located in the hypothalamus. Carotid sinus contains baroreceptors, not osmoreceptors.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which statement(s) about glucose reabsorption in the renal tubule are correct? (1) Glucose is reabsorbed in the proximal tubule. (2) Glucose reabsorption from the tubule lumen occurs by a Na+-dependent transporter, SGLT. (3) Glucose moves out of the tubule cell into the interstitial fluid by a K+-linked process. (4) At a normal plasma glucose concentration, glucose is filtered at the glomerulus and secreted into the urine.", "options": [ "1, 2", "2, 3", "1, 3", "2, 4", "1, 4" ], "a": 0, "e": "Statements 1 and 2 are true: glucose is reabsorbed in the proximal tubule via the Na+-dependent SGLT cotransporter. (3) is false (exit is GLUT/facilitated, not K+-linked); (4) is false (at normal glucose it is fully reabsorbed, not secreted).", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Which force is the primary pressure favoring filtration across the glomerular capillary?", "options": [ "Tubular fluid osmotic pressure", "Peritubular capillary pressure", "Osmotic force due to proteins in the plasma", "Glomerular capillary hydrostatic pressure", "Bowman's space hydrostatic pressure" ], "a": 3, "e": "Glomerular capillary hydrostatic pressure (PGC ~60 mmHg) is the only force favoring filtration; PBS and plasma protein osmotic pressure (piGC) oppose it. Net filtration = PGC - PBS - piGC.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "A physiologically realistic increase in Bowman's space hydrostatic pressure (PBS) would have which effect on glomerular filtration:", "options": [ "Stop filtration", "Have no effect on filtration", "Reverse filtration direction", "Increase filtration", "Decrease filtration" ], "a": 4, "e": "Bowman's space hydrostatic pressure (PBS) opposes filtration in the equation NFP = PGC - PBS - piGC. A realistic increase in PBS lowers net filtration pressure, decreasing GFR (it does not fully stop or reverse filtration).", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "A patient has an increase in tubular flow past the macula densa. What is the immediate effect on the afferent arteriole?", "options": [ "It dilates, increasing GFR", "No change occurs", "It constricts, decreasing GFR", "It constricts, increasing glomerular pressure", "It dilates, decreasing glomerular pressure" ], "a": 2, "e": "Tubuloglomerular feedback: increased NaCl flow past the macula densa releases paracrine signals that constrict the afferent arteriole, decreasing GFR (autoregulation). Confirmed by Vander JGA and standard TGF references.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Constriction of the afferent arteriole causes which change?", "options": [ "Increased surface area of glomerular capillaries", "Decreased resistance entering the glomerulus", "Decreased hydrostatic pressure in the glomerulus", "Increased hydrostatic pressure in the glomerulus", "Increased GFR" ], "a": 2, "e": "Constricting the afferent arteriole reduces blood flow into the glomerulus, lowering glomerular capillary hydrostatic pressure and therefore GFR.", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "The macula densa is best described as:", "options": [ "Cells located in Bowman's capsule that regulate filtration surface area", "Cells in the distal tubule wall that sense increased fluid flow", "Cells that form part of the renal corpuscle", "Cells that directly increase glomerular hydrostatic pressure", "A group of smooth muscle cells surrounding the afferent arteriole" ], "a": 1, "e": "The macula densa is specialized cells of the distal tubule (early DCT/thick ascending limb) wall that sense tubular NaCl/flow and signal the afferent arteriole (tubuloglomerular feedback).", "_mod": "renal", "src": "course", "exam": "final-practice" }, { "q": "Endocrine glands:", "options": [ "require neural input to initiate hormone secretion.", "store their secretions in hollow chambers before release.", "release their secretions onto epithelial surfaces.", "lack ducts and secrete hormones directly into the bloodstream.", "release their secretions onto body surfaces." ], "a": 3, "e": "Endocrine glands are ductless and release hormones directly into the interstitial fluid/blood. Exocrine glands (not endocrine) secrete into ducts onto surfaces; neural input is not required for all endocrine secretion.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Hormones are:", "options": [ "used as an energy source.", "biologically inert by themselves.", "have high potency.", "always stored in secretory granules.", "incorporated as a structural moiety into another molecule." ], "a": 2, "e": "Hormones are highly potent, acting at very low (nano/picomolar) plasma concentrations. They are not energy sources, are biologically active (not inert), are not structural moieties, and only steroids are NOT pre-stored (made on demand), so 'always stored' is false.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which of the following is not a function of binding proteins?", "options": [ "Prevent hormone degradation", "Mediate hormonal effects", "Bind steroid hormones", "Bind thyroid hormones", "Prevent clearance of hormones" ], "a": 1, "e": "Binding proteins bind steroid/thyroid hormones, protect from degradation/clearance, and form a free-hormone reservoir. They do NOT mediate hormonal effects—only free, unbound hormone reaches target cells and exerts the biological effect.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "The actions of protein hormones are usually mediated by:", "options": [ "endocytic vesicles.", "cytoplasmic receptors.", "nuclear receptors.", "exocytic vesicles.", "second messengers." ], "a": 4, "e": "Protein/peptide hormones bind plasma-membrane receptors and act via second messengers (cAMP, Ca2+, IP3) and receptor-associated enzymes. They are too hydrophilic to enter the cell, so cytoplasmic/nuclear receptors and exo/endocytic vesicles are not the mediators.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which statement best describes how steroid hormones exert their effects on target cells?", "options": [ "They bind to cell-surface receptors and activate second messenger systems.", "They require membrane ion channels to enter the cell.", "They are stored in secretory vesicles and released by exocytosis.", "They bind to intracellular receptors that directly regulate gene transcription.", "They act only on cells with gap junctions." ], "a": 3, "e": "Steroid hormones are lipophilic, cross the plasma membrane, and bind intracellular (nuclear-superfamily) receptors that directly alter gene transcription. They do not use cell-surface receptors/second messengers, ion channels, vesicular release, or gap junctions for their primary action.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "The receptors for non-steroid peptide hormones are found on the ______.", "options": [ "Golgi apparatus.", "mitochondria.", "plasma membrane.", "nuclear envelope.", "lysosomes." ], "a": 2, "e": "Non-steroid (peptide) hormones are water-soluble and cannot cross the membrane, so their receptors are located on the plasma membrane (extracellular surface) of target cells. Steroid/thyroid receptors are intracellular by contrast.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Oxytocin and antidiuretic hormone (ADH; vasopressin) are:", "options": [ "complex steroids.", "released from the anterior pituitary where blood is hypotonic.", "synthesized in the hypothalamus and released from the posterior pituitary.", "two names for the same hormone.", "synthesized and stored in the posterior pituitary." ], "a": 2, "e": "Oxytocin and ADH/vasopressin are peptides synthesized in hypothalamic cell bodies (supraoptic/paraventricular nuclei), transported down axons, and released from the posterior pituitary. They are not steroids, not the same hormone, and not synthesized in the posterior pituitary itself.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which of the following best describes the primary antidiuretic action of antidiuretic hormone (ADH)?", "options": [ "It decreases blood pressure by dilating renal blood vessels.", "It increases water permeability of the renal collecting ducts by inserting aquaporin-2 channels.", "It reduces thirst by inhibiting hypothalamic osmoreceptors.", "It stimulates aldosterone secretion from the adrenal cortex.", "It decreases sodium reabsorption in the distal convoluted tubule." ], "a": 1, "e": "ADH's primary antidiuretic action is increasing water permeability of the collecting ducts by inserting aquaporin-2 channels into the apical membrane (via V2 receptor/cAMP), allowing water reabsorption. It does not stimulate aldosterone, reduce thirst, or decrease Na+ reabsorption as its primary action.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Oxytocin:", "options": [ "participates in a positive feedback loop that strengthens uterine contractions during labor.", "secretion increases with psychological stress.", "is primarily synthesized in the supraoptic nuclei.", "deficiency results in impaired stress-induced cortisol release.", "is secreted from the anterior pituitary." ], "a": 0, "e": "Oxytocin participates in a positive feedback loop during labor: uterine/cervical stretch reflexively triggers oxytocin release, strengthening contractions. It is secreted from the posterior (not anterior) pituitary and is classically associated with the paraventricular (not supraoptic) nucleus.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Anti-diuretic hormone (ADH) secretion is:", "options": [ "increased by alcohol.", "reduced by increased blood osmolality.", "increased in hypothalamic diabetes insipidus.", "increased during stress.", "reduced during hemorrhage." ], "a": 3, "e": "ADH secretion is increased during stress (surgical/pain/nausea). Alcohol inhibits ADH (A false); increased osmolality stimulates ADH (B false); hypothalamic/central DI is ADH-deficient (C false); hemorrhage/hypovolemia increases ADH (E false).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Oxytocin:", "options": [ "inhibits sperm swimming on the gonad.", "inhibits myometrial contraction.", "inhibits production of milk.", "promotes orgasm.", "is bound to neurophysin in plasma." ], "a": 4, "e": "Oxytocin (with ADH) is synthesized as a prohormone and is carried/bound to neurophysin, with which it is co-secreted into plasma. The other options are false: oxytocin STIMULATES myometrial contraction and milk ejection; it does not inhibit sperm or cause orgasm.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "The posterior pituitary stores and secretes _________.", "options": [ "growth hormone and thyroid-stimulating hormone.", "aldosterone and cortisol.", "luteinizing hormone and follicle-stimulating hormone.", "anti-diuretic hormone (ADH) and oxytocin.", "estrogen and testosterone." ], "a": 3, "e": "The posterior pituitary stores and secretes ADH (vasopressin) and oxytocin, synthesized in hypothalamic supraoptic/paraventricular nuclei. GH/TSH/LH/FSH/prolactin are anterior pituitary; aldosterone/cortisol/sex steroids are not pituitary.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "The anterior pituitary:", "options": [ "is neural tissue.", "is regulated by hypothalamic neuropeptides.", "synthesizes steroid hormones.", "is an exocrine gland.", "lies just above the kidney." ], "a": 1, "e": "The anterior pituitary is an endocrine gland regulated by hypothalamic hypophysiotropic hormones (neuropeptides) via the portal system. It is NOT neural tissue (that is the posterior lobe), does not make steroids, is not exocrine, and lies in the sella turcica, not above the kidney.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Growth hormone:", "options": [ "is released during sleep.", "is released in response to somatostatin.", "stimulates its own secretion.", "excess induces gigantism in adults.", "is the only pituitary hormone synthesized from cholesterol." ], "a": 0, "e": "GH is released during sleep (large bursts 1-2 h after falling asleep). It is inhibited (not released) by somatostatin; does not stimulate its own secretion; GH excess in ADULTS causes acromegaly (gigantism is pre-puberty); and GH is a peptide, not made from cholesterol.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Growth hormone:", "options": [ "secretion decreases during sleep.", "secretion is diurnal.", "secretion increases with aging.", "causes hypoglycemia.", "causes growth of soft tissue." ], "a": 1, "e": "Vander's 16e Ch11: GH secretion \"occurs in episodic bursts and manifests a striking daily rhythm\" with a large surge 1-2 h after sleep onset (diurnal). Opt0 false (rises in sleep), Opt2 false (falls with aging), Opt3 false (anti-insulin = hyperglycemia, Ch11/Ch16). Opt4 loose: GH's headline effect is bone+muscle, \"soft tissue\" is acromegaly framing. Opt1 verbatim-supported.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "A person with acromegaly usually has:", "options": [ "a growth hormone deficiency.", "decreased production of somatomedins and insulin-like growth factors.", "protruding eyeballs.", "hypoglycemia.", "prognathism and large fleshy lips." ], "a": 4, "e": "Acromegaly (GH/IGF-1 excess in adults) causes bone thickening and prognathism (enlarged jaw) with coarse/fleshy facial features. It involves GH EXCESS, INCREASED IGF-1/somatomedins, hyperglycemia (anti-insulin), not exophthalmos (that is Graves' disease).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which hypothalamic hormone inhibits growth hormone (GH) secretion from the anterior pituitary?", "options": [ "Corticotropin-releasing hormone (CRH)", "Somatostatin (growth hormone-inhibiting hormone, GHIH)", "Thyrotropin-releasing hormone (TRH)", "Growth hormone-releasing hormone (GHRH)", "Gonadotropin-releasing hormone (GnRH)" ], "a": 1, "e": "Somatostatin (growth hormone-inhibiting hormone, GHIH) inhibits GH secretion from the anterior pituitary. GHRH stimulates GH; CRH/TRH/GnRH control ACTH/TSH/gonadotropins respectively.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which of the following is the primary physiological role of prolactin?", "options": [ "Regulation of thyroid hormone secretion", "Promotion of linear bone growth", "Stimulation of milk production in the mammary glands", "Stimulation of adrenal cortisol release", "Induction of ovulation" ], "a": 2, "e": "Prolactin's primary role is stimulating development of mammary glands and milk production (lactation). It does not regulate thyroid/adrenal secretion, promote bone growth, or induce ovulation (LH surge does that).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Thyroid-stimulating hormone (TSH):", "options": [ "has gonadotropic activity.", "secretion is increased by an increase in T4 (thyroxine) levels.", "is synthesized in the follicular cells of the thyroid gland.", "stimulates the activity of parafollicular thyroid cells.", "is a glycoprotein hormone." ], "a": 4, "e": "TSH is a glycoprotein hormone (like FSH and LH). It lacks gonadotropic activity; its secretion is DECREASED by elevated T4 (negative feedback); it is made in the anterior pituitary (not thyroid follicular cells); and it stimulates follicular, not parafollicular, cells.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Thyroid-stimulating hormone (TSH):", "options": [ "induces goitre formation when chronically elevated.", "is a template for thyroid hormone biosynthesis.", "is synthesized in parafollicular cells.", "is derived from iodinated tyrosine residues.", "secretion is inhibited by TRH from the hypothalamus." ], "a": 0, "e": "Chronically elevated TSH causes thyroid hypertrophy → goitre. TSH is not a template (thyroglobulin is); it is made in the anterior pituitary (not parafollicular cells); it is a glycoprotein, not iodinated tyrosine; and TRH STIMULATES (not inhibits) TSH.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Thyroid hormones (T3 and T4):", "options": [ "stimulate the secretion of thyroid-stimulating hormone (TSH; thyrotropin).", "are steroid hormones synthesized from cholesterol.", "contain iron atoms in ferrous form.", "increase metabolic rate.", "are hydrophilic as they are made from amino acids." ], "a": 3, "e": "Thyroid hormones increase metabolic rate (calorigenic effect). They INHIBIT TSH (negative feedback); are amine/tyrosine derivatives (not steroids from cholesterol); contain iodine (not iron); and are lipophilic/poorly water-soluble (bound to plasma proteins).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which statement regarding thyroid hormone transport in plasma is TRUE?", "options": [ "Thyroid-binding prealbumin binds both T3 and T4 equally", "Thyroid-binding globulin (TBG) binds only T3", "The majority of circulating thyroid hormone is bound to thyroid hormone binding proteins.", "Most circulating T3 and T4 are in the free (unbound) form", "Binding proteins decrease the half-life of thyroid hormones" ], "a": 2, "e": "The great majority (>99%) of circulating T3/T4 is reversibly bound to plasma proteins (TBG, transthyretin, albumin); only a tiny free fraction is active. Binding proteins prolong (not shorten) half-life.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which of the following is a physiological action of thyroid hormones?", "options": [ "Decreased basal metabolic rate and heat production", "Decreased oxygen consumption in peripheral tissues", "Enhanced growth and central nervous system development", "Reduced β-adrenergic receptor expression", "Increased plasma cholesterol levels" ], "a": 2, "e": "Thyroid hormone is essential for normal growth (required for GH production) and is a key developmental hormone for the CNS (axon/synapse/dendrite/myelin formation). A, B, D are reversed (T3 raises BMR, O2 use, beta-adrenergic receptors); E wrong (T3 lowers cholesterol).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Cortisol secretion is directly stimulated by:", "options": [ "Aldosterone", "High blood potassium", "ACTH", "CRH", "Prolactin" ], "a": 2, "e": "ACTH from the anterior pituitary directly stimulates the adrenal cortex to secrete cortisol. CRH acts on the pituitary to release ACTH (one step removed), so the DIRECT stimulus is ACTH, not CRH.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Cortisol helps the body respond to stress primarily by which mechanism?", "options": [ "Increasing immune cell proliferation", "Increasing aldosterone secretion", "Enhancing inflammatory responses to injury", "Preventing inflammation and autoimmunity", "Suppressing hepatic glucose production" ], "a": 3, "e": "Cortisol's protective stress action includes anti-inflammatory/anti-immune effects ('brake' on the immune system), preventing inflammation and autoimmunity. A and C are reversed (cortisol suppresses immunity/inflammation); E reversed (cortisol raises hepatic glucose); B is not a cortisol action.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which statement correctly describes the regulation of cortisol secretion?", "options": [ "Cortisol secretion is independent of hypothalamic input", "Cortisol secretion follows a diurnal rhythm regulated by light-dark cycles", "Cortisol release is constant throughout the 24-hour cycle", "ACTH directly inhibits cortisol release from the adrenal cortex", "Peak cortisol levels occur at midday during wakefulness" ], "a": 1, "e": "Cortisol follows a circadian/diurnal rhythm: CRH secretion is tied to the day/night (light-dark) cycle, so ACTH and cortisol rise in the hours before awakening. A, C false; D reversed (ACTH stimulates); E false (peak is early morning, not midday).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Aldosterone:", "options": [ "will increase potassium excretion.", "is over-produced in Addison's disease.", "is released by an increase in extracellular fluid volume.", "is released in response to angiotensinogen.", "will increase water loss." ], "a": 0, "e": "Aldosterone stimulates renal Na+/H2O retention and K+/H+ excretion, so it increases potassium excretion. B false (deficient, not over-produced, in Addison's); C false (raised ECF volume suppresses it); D false (responds to angiotensin II, not angiotensinogen); E false (retains water).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Aldosterone:", "options": [ "is synthesized in the zona fasciculata.", "is deficient in Conn's syndrome.", "is not derived from cholesterol.", "secretion is primarily regulated by ACTH.", "is released from the adrenal cortex." ], "a": 4, "e": "Aldosterone is released from the adrenal cortex (zona glomerulosa). A false (glomerulosa, not fasciculata); B false (Conn's = primary hyperaldosteronism = excess); C false (it is a cholesterol-derived steroid); D false (regulated mainly by angiotensin II/renin and plasma K+, not ACTH).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Blood calcium is elevated:", "options": [ "in pseudohypoparathyroidism.", "by Vitamin D3.", "in Osteomalacia.", "in rickets.", "by calcitonin." ], "a": 1, "e": "Vitamin D3 (active 1,25-(OH)2D) raises plasma Ca2+ by promoting intestinal Ca2+ absorption; excess vitamin D causes hypercalcemia. A (PTH resistance), C (osteomalacia), D (rickets) all reflect vit D deficiency/low Ca2+; E wrong (calcitonin lowers Ca2+).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Increased parathyroid hormone (PTH) concentration is associated with:", "options": [ "vitamin D toxicity.", "enhanced bone mineralization.", "reduced excretion of phosphate.", "weak bones.", "increased osteoblast activity in bone." ], "a": 3, "e": "Excess PTH increases osteoclastic bone resorption, moving Ca2+ out of bone -> weakened bone (hyperparathyroidism causes bone loss). A false (vit D toxicity suppresses PTH); B false (resorption not mineralization); C false (PTH increases phosphate excretion); E false (net resorptive).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Parathyroid hormone:", "options": [ "is secreted by osteoblasts and osteoclasts.", "is secreted in increased amounts when blood calcium level is below normal.", "causes development of goitre.", "increases deposition of calcium in bones.", "is the molecule formed when T4 and T3 are degraded." ], "a": 1, "e": "Decreased plasma Ca2+ directly stimulates PTH secretion from parathyroid chief cells. A false (parathyroid gland cells, not osteoblasts/clasts); C false (no goitre); D false (PTH releases Ca2+ from bone, not deposition); E false (unrelated to thyroid hormone degradation).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which of the following best describes the overall effect of parathyroid hormone (PTH) on plasma calcium and phosphate levels?", "options": [ "Increases plasma calcium and decreases plasma phosphate", "Decreases plasma calcium and increases plasma phosphate", "Has no effect on plasma calcium or phosphate", "Decreases both plasma calcium and phosphate", "Increases both plasma calcium and phosphate" ], "a": 0, "e": "PTH increases plasma calcium (bone resorption, renal Ca2+ reabsorption, 1,25-(OH)2D-driven gut absorption) while decreasing plasma phosphate via its dominant phosphaturic renal action (decreased phosphate reabsorption -> increased excretion).", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "Which hormone is classified as a hypocalcemic hormone and is secreted by the parafollicular (C) cells of the thyroid gland?", "options": [ "Calcitonin", "Parathyroid hormone (PTH)", "Vitamin D3 (1,25-dihydroxyvitamin D)", "Aldosterone", "Cortisone" ], "a": 0, "e": "Calcitonin is the hypocalcemic peptide secreted by parafollicular (C) cells of the thyroid; it lowers plasma Ca2+ mainly by inhibiting osteoclastic bone resorption. PTH and 1,25-(OH)2D raise Ca2+; aldosterone/cortisone are adrenal steroids.", "_mod": "endo", "src": "course", "exam": "final-practice" }, { "q": "In a normal healthy, 25 year old woman with a menstrual cycle of 28 days:", "options": [ "The concentration of progesterone in the plasma is high during the follicular phase and falls during the luteal phase.", "A surge in progesterone levels causes ovulation.", "Ovulation occurs on Day 1 of the menstrual cycle.", "During the secretory phase of the uterine cycle, there is increased vascularization and development of uterine glands.", "The corpus luteum forms during the follicular phase of the ovarian cycle." ], "a": 3, "e": "Secretory (luteal) phase: progesterone from the corpus luteum makes endometrium secretory with increased vascularization and coiled uterine glands. A is reversed (progesterone is low in follicular phase), B false (LH surge triggers ovulation), C false (ovulation ~day 14), E false (corpus luteum forms in luteal phase).", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "A person with an XY karyotype who is outwardly female, has no male or female internal duct systems, and develops breasts due to peripheral conversion of androgens most likely has:", "options": [ "5-alpha reductase deficiency", "Turner syndrome", "Androgen insensitivity syndrome", "Klinefelter syndrome", "Congenital adrenal hyperplasia" ], "a": 2, "e": "Androgen insensitivity syndrome: XY genotype, testes secrete AMH (regresses Müllerian) and testosterone, but defective androgen receptor means Wolffian ducts also regress, so 'no duct system develops'; external phenotype is female and breasts form via peripheral aromatization of androgens to estrogen.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which factor directly causes regression of the Müllerian ducts during male sexual differentiation?", "options": [ "Luteinizing hormone (LH)", "Testosterone", "Estrogen", "Dihydrotestosterone (DHT)", "Müllerian inhibiting hormone (MIH)" ], "a": 4, "e": "Müllerian inhibiting hormone (MIH/AMH), secreted by fetal testis Sertoli cells under SRY, directly causes degeneration of the Müllerian ducts in males. Testosterone/DHT act on Wolffian ducts and external genitalia, not Müllerian regression.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "In Turner's syndrome:", "options": [ "The individual (male) inherits only one Y chromosome.", "The individual (male) inherits two Y chromosomes.", "The individual (male) inherits two X chromosomes and a Y chromosome.", "The individual (female) inherits only one X chromosome.", "The individual (female) inherits three X chromosomes." ], "a": 3, "e": "Turner syndrome is 45,X: a phenotypic female inheriting only one X chromosome (monosomy X). Options describing males are wrong (Turner individuals are female); three X is triple-X, not Turner.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which of the following factors inhibits uterine (myometrial) contractions during pregnancy?", "options": [ "Progesterone", "Prostaglandins", "Oxytocin", "Stretch of the uterus", "Estrogen" ], "a": 0, "e": "Progesterone inhibits myometrial contractions, maintaining uterine quiescence during pregnancy so the fetus is not expelled prematurely. Prostaglandins, oxytocin, uterine stretch, and estrogen all promote/stimulate contractions.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which hormone produced by the placenta is responsible for maintaining the corpus luteum during early pregnancy?", "options": [ "Human placental lactogen (hPL)", "Estrogen", "Progesterone", "Human chorionic gonadotropin (hCG)", "Prolactin" ], "a": 3, "e": "Human chorionic gonadotropin (hCG), secreted by trophoblast/placenta, rescues and maintains the corpus luteum in early pregnancy so it continues secreting progesterone/estrogen until the placenta takes over.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which of the following statements regarding the placenta is correct? (1) The placenta allows fetal and maternal blood to mix. (2) The placenta releases human chorionic gonadotropin (hCG) which maintains the corpus luteum during the early stages of pregnancy. (3) The placenta acts as an immunological barrier. (4) The placenta contains enzymes to synthesize androgens from progesterone.", "options": [ "1, 2", "3, 4", "1, 4", "1, 3", "2, 3" ], "a": 4, "e": "Statements 2 and 3 true: placenta releases hCG (maintains corpus luteum) and acts as an immunological barrier. (1) false—fetal and maternal blood do NOT mix; (4) false—placenta has enzymes for progesterone but lacks those to form androgens (relies on fetal adrenal precursors).", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which of the following secretes enzymes and citrate into the urethra during ejaculation?", "options": [ "bulbourethral gland", "seminal vesicle", "prostate gland", "vas deferens", "epididymis" ], "a": 2, "e": "The prostate gland secretes a milky fluid containing citrate, calcium, and enzymes (clotting enzyme/profibrinolysin, PSA) into the urethra during ejaculation. Seminal vesicles supply fructose/prostaglandins; bulbourethral glands supply mucus.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "In a normal healthy male, which of the following is not correct?", "options": [ "An increase in inhibin release would cause an increase in FSH secretion.", "GnRH is released from the hypothalamus.", "FSH stimulates Sertoli cells to release ABP (androgen binding protein).", "Inhibin can only act at the level of the anterior pituitary.", "LH causes Leydig cells to release testosterone." ], "a": 0, "e": "NOT correct: increased inhibin DECREASES (not increases) FSH secretion via negative feedback. B, C, E are true (GnRH from hypothalamus; FSH→Sertoli→ABP; LH→Leydig→testosterone). D is also true in Vander (inhibin acts mainly at the anterior pituitary), so A is the false statement.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which event directly establishes the block to polyspermy after a sperm successfully fuses with the oocyte?", "options": [ "Migration of male and female pronuclei to the center of the zygote", "Capacitation of sperm within the female reproductive tract", "Release of cortical granules that modify and harden the zona pellucida", "Binding of sperm to receptors on the zona pellucida", "Completion of the first meiotic division of the oocyte" ], "a": 2, "e": "After sperm-egg fusion, the cortical reaction releases cortical granules whose enzymes inactivate zona sperm-binding sites and harden the zona pellucida, establishing the (slow) block to polyspermy. Binding to zona and capacitation precede fusion; pronuclear migration/meiosis II occur afterward.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Why is the timing of fertilization limited in humans?", "options": [ "Sperm are viable for only 12-24 hours", "The oocyte is viable for only 12-24 hours after ovulation", "Polyspermy blocks fertilization within minutes of ejaculation", "The zona pellucida hardens immediately after ovulation", "Capacitation prevents sperm from surviving longer than 24 hours" ], "a": 1, "e": "The ovulated oocyte is viable only a short time (~24-48 h) after ovulation, which limits the fertilization window; sperm survive longer (~4-6 days). Among the options, only B captures the correct limiting factor (brief oocyte viability). A, C, D, E misstate sperm viability/polyspermy/zona timing.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which hormonal change triggers the menstrual phase of the uterine cycle?", "options": [ "Increased progesterone secretion from the corpus luteum", "Increased estrogen and progesterone due to ovulation", "Increased estrogen stimulation of the endometrium", "Increased FSH and LH secretion from the pituitary", "Decreased estrogen and progesterone following corpus luteum degeneration" ], "a": 4, "e": "The menstrual phase is triggered by the fall in plasma estrogen and progesterone caused by degeneration of the corpus luteum, which withdraws hormonal support, causing endometrial vasoconstriction, sloughing, and menstrual flow.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Indicate which day of the 28 day menstrual cycle is correctly matched with the event:", "options": [ "Day 1 – A dominant follicle is selected", "Day 23 – Progesterone secretion peaks from the corpus luteum", "Day 28 – Estrogen levels peak", "Day 7 – An LH surge occurs due to the absence of progesterone", "Day 13 – The corpus luteum is formed" ], "a": 1, "e": "Progesterone from the corpus luteum peaks at ~day 23 (luteal phase). Vander's own matching key pairs 'progesterone peaks' with day 23. Distractors are mismatched: dominant follicle is selected ~day 7, estrogen peaks ~day 12-13, LH surge ~day 14, corpus luteum forms after ovulation.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Implantation of the blastocyst occurs _________ after fertilization in the _________.", "options": [ "6 to 7 days; endometrium", "24 to 36 hours; endometrium", "6 to 7 days; uterine tube", "24 to 36 hours; myometrium", "6 to 7 days; myometrium" ], "a": 0, "e": "Implantation of the blastocyst into the endometrium occurs about 6-7 days after ovulation/fertilization. It embeds in the endometrium (uterine lining), not the myometrium or uterine tube.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Regression of the Wolffian duct in females is due to the:", "options": [ "absence of testosterone.", "absence of growth hormone.", "presence of estrogen.", "absence of Mullerian inhibiting hormone (MIH).", "presence of progesterone." ], "a": 0, "e": "In females (no testes, no testosterone), the Wolffian ducts degenerate due to the absence of testosterone, while the Mullerian ducts persist (forming uterine tubes/uterus) because AMH is absent.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "At which stage is meiosis I completed during human oogenesis?", "options": [ "At puberty, in all primary oocytes", "During fetal life, before birth", "At implantation of the embryo", "Just prior to ovulation in the dominant follicle", "Immediately after fertilization" ], "a": 3, "e": "Primary oocytes are arrested in meiosis I from fetal life. Only the oocyte destined for ovulation completes meiosis I, which occurs just before ovulation in the dominant follicle, producing a secondary oocyte and first polar body.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "During the early to mid-follicular phase of the ovarian cycle, which hormonal interaction is primarily responsible for increasing estrogen production?", "options": [ "LH stimulates granulosa cells to secrete estrogen directly", "Inhibin increases FSH secretion to raise estrogen levels", "LH stimulates theca cells to secrete androgens that are converted to estrogen in granulosa cells", "Progesterone stimulates aromatase activity in theca cells", "FSH stimulates theca cells to secrete estrogen" ], "a": 2, "e": "In the early/mid-follicular phase, LH stimulates theca cells to make androgens (granulosa cells lack the enzymes); the androgens diffuse into granulosa cells where aromatase converts them to estrogen, driven by FSH.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which statement best describes the functional significance of the follicular phase of the ovarian cycle?", "options": [ "It allows selection and maturation of a dominant follicle capable of ovulation", "It directly causes menstruation", "It supports early pregnancy by preventing uterine contractions", "It prepares the uterus for implantation by maintaining progesterone levels", "It triggers regression of the corpus luteum" ], "a": 0, "e": "The functional significance of the follicular phase is selection and maturation of a dominant follicle capable of ovulation. Menstruation, implantation prep, and corpus luteum support are functions of other phases.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "At birth, most of the \"eggs\" in a female's ovaries are in the form of ___________. When an \"egg\" is ovulated it is in the form of a/an __________.", "options": [ "oogonia; secondary oocyte", "primary oocytes; secondary oocyte", "secondary oocytes; ovum", "first polar bodies; secondary oocyte", "primary oocytes; primary oocyte" ], "a": 1, "e": "At birth all eggs are primary oocytes arrested in meiosis I. An ovulated egg is a secondary oocyte (meiosis II is completed only if fertilized). Oogonia are gone by birth; the ovum stage requires fertilization.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which is true for the process of gametogenesis (i.e. spermatogenesis and/or oogenesis)?", "options": [ "Two equal sized cells are formed after the first meiotic division in oogenesis.", "During mitosis in oogenesis, one of the daughter cells rejoins the original pool to maintain the number of oogonia in the pool.", "In spermatogenesis the number of spermatogonia is established prior to birth.", "Oogenesis produces four haploid cells, whereas spermatogenesis produces only one functional spermatozoan.", "Oogenesis produces one functional ovum, whereas spermatogenesis produces four functional spermatozoa." ], "a": 4, "e": "Oogenesis yields only one functional ovum per primary oocyte (the rest become nonfunctional polar bodies), whereas each primary spermatocyte produces four viable spermatozoa. Meiosis I in oogenesis gives unequal-sized cells.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "The acrosome functions to:", "options": [ "increase the sperm's mobility.", "transport the sperm to the oocyte.", "store enzymes which allow the sperm to digest a 'path' through the zona pellucida to the oocyte.", "store energy needed for the swimming movement of the tail.", "direct the sperm to the oocyte." ], "a": 2, "e": "The acrosome is a protein-filled vesicle at the sperm head containing enzymes that, upon the acrosome reaction, digest a path through the zona pellucida to reach the oocyte. It is not for motility, energy, or guidance.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "In the hypothalamic-pituitary-testicular axis:", "options": [ "Testosterone does not exert negative feedback effects at either the level of the anterior pituitary or at the level of the hypothalamus.", "High frequency pulses of GnRH favor the release of FSH (follicle-stimulating hormone) from the anterior pituitary.", "The Leydig cells release inhibin.", "Inhibin released from Sertoli cells acts at the level of the hypothalamus to inhibit GnRH (gonadotropin-releasing hormone) secretion.", "LH (luteinizing hormone) acts on the Leydig cells to release testosterone." ], "a": 4, "e": "LH acts on Leydig (interstitial) cells to stimulate testosterone secretion. Other options are false: testosterone does exert negative feedback; high-frequency GnRH favors LH (not FSH); inhibin is from Sertoli (not Leydig) cells and acts on the pituitary.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "What is the primary mechanism responsible for movement of the ovum through the uterine tube?", "options": [ "Diffusion", "Hormonal action", "Gravity", "Ciliary action", "Peristaltic contractions only" ], "a": 3, "e": "Vander: within the fallopian tube, egg movement is 'driven almost entirely by fallopian-tube cilia' (smooth-muscle peristalsis is minor). Ciliary action is the primary mechanism.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which uterine layer is the thickest and is composed primarily of smooth muscle?", "options": [ "Perimetrium", "Endometrium", "Myometrium", "Basal layer", "Cervical canal" ], "a": 2, "e": "The myometrium is the thick middle layer of uterine smooth muscle (Vander: estrogen stimulates the 'underlying uterine smooth muscle, called the myometrium'). Endometrium is the inner mucosa; perimetrium the thin serosa.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Each mitotic division of a spermatogonium produces 1 ________________ and 1 ________________, which is destined to undergo meiosis.", "options": [ "primary spermatocyte; secondary spermatocyte", "secondary spermatocyte; primary spermatocyte", "spermatogonium; secondary spermatocyte", "spermatid; primary spermatocyte", "spermatogonium; primary spermatocyte" ], "a": 4, "e": "Spermatogonial mitosis uses stem-cell renewal: one daughter stays a spermatogonium (stem cell), the other becomes a primary spermatocyte destined for meiosis. Matches stem 'destined to undergo meiosis.'", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "A single secondary spermatocyte:", "options": [ "undergoes meiotic division to produce 2 spermatids.", "undergoes mitosis to produce 2 spermatids.", "divides to produce a first polar body.", "undergoes meiotic division to produce spermatogonia.", "has a diploid number of chromosomes." ], "a": 0, "e": "Each secondary spermatocyte (haploid, 23 two-chromatid chromosomes) undergoes the second MEIOTIC division to form 2 spermatids. Polar bodies/diploid apply to oogenesis or earlier stages, not this cell.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Luteinizing hormone (LH):", "options": [ "secretion is inhibited by GnRH.", "stimulates androgen secretion.", "is secreted from the posterior pituitary.", "acts on Sertoli cells to stimulate testosterone release.", "stimulates spermatogenesis." ], "a": 1, "e": "LH acts on Leydig cells to stimulate testosterone (androgen) secretion. It is from the ANTERIOR pituitary (not posterior), acts on Leydig (not Sertoli); spermatogenesis is driven by FSH/local testosterone; GnRH stimulates (not inhibits) LH.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which phase of the male sexual response is primarily controlled by the parasympathetic nervous system?", "options": [ "Emission", "Acrosome reaction", "Erection", "Sperm transport", "Ejaculation" ], "a": 2, "e": "Erection is the parasympathetic-mediated vasodilatory phase (NO release, sympathetic inhibition); emission/ejaculation are sympathetic. Standard 'point (PNS) and shoot (SNS).' Acrosome reaction/sperm transport are not male-response phases.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Where do sperm acquire motility and become concentrated after being released from the seminiferous tubules?", "options": [ "Epididymis", "Vas deferens", "Ejaculatory duct", "Prostate gland", "Seminiferous tubules" ], "a": 0, "e": "Sperm leaving the seminiferous tubules are nonmotile; during passage through the epididymis they become concentrated (fluid absorption) and mature/acquire motility. Vander: 'enter the epididymis, where the sperm are concentrated and become mature.'", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which process is responsible for halving the chromosome number during spermatogenesis?", "options": [ "Differentiation", "Spermiogenesis", "Mitosis", "Meiosis", "Capacitation" ], "a": 3, "e": "Meiosis (two divisions, one round of DNA replication) reduces chromosome number from 46 to 23. Mitosis maintains 46; spermiogenesis/differentiation are remodeling steps; capacitation occurs in the female tract.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which hormone secreted by Sertoli cells functions as part of a negative feedback loop for FSH?", "options": [ "Testosterone", "Androgen-binding protein", "Gonadotropin-releasing hormone (GnRH)", "Luteinizing hormone (LH)", "Inhibin" ], "a": 4, "e": "Sertoli cells secrete the protein hormone inhibin, which acts on the anterior pituitary as a negative-feedback inhibitor of FSH. Testosterone is from Leydig cells; ABP is a binding protein, not a feedback hormone; GnRH/LH are not Sertoli products.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which hormonal change is the primary trigger for the onset of puberty?", "options": [ "Decreased secretion of inhibin from the gonads", "Increased estrogen secretion from the ovaries", "Increased prolactin secretion from the anterior pituitary", "Increased pulsatile secretion of GnRH from the hypothalamus", "Increased sensitivity of the pituitary to negative feedback" ], "a": 3, "e": "Puberty is triggered by increased amplitude/pulse frequency of hypothalamic GnRH secretion (driven by kisspeptin), raising gonadotropins. Brain becomes LESS sensitive to negative feedback (so E is wrong); the gonadal-steroid rises are downstream.", "_mod": "repro", "src": "course", "exam": "final-practice" }, { "q": "Which cell type in the testes is primarily responsible for secreting testosterone?", "options": [ "Sertoli cells", "Spermatogonia", "Leydig (interstitial) cells", "Sustentacular cells", "Myoid (smooth muscle) cells" ], "a": 2, "e": "Leydig (interstitial) cells synthesize and release testosterone (stimulated by LH). Sertoli/sustentacular cells nourish germ cells and secrete inhibin/ABP; spermatogonia are germ cells; myoid cells provide contractile support.", "_mod": "repro", "src": "course", "exam": "final-practice" } ] } }; const COVERAGE_CARDS = { "cns": [ { "t": "The three meninges (outer → inner)", "d": "Dura mater (outer, next to bone) → arachnoid mater (middle) → pia mater (inner, adheres to brain/cord). CSF fills the subarachnoid space between arachnoid and pia. (Exam: innermost→outermost is pia, arachnoid, dura.)", "topic": "Protective elements of the CNS: meninges, CSF/ventricles/choroid plexus, and the blood-brain barrier", "citation": "CNS Study Notes 2025 'The Meninges' (lines 106-117): 'Dura mater - Outer layer... Arachnoid mater - Intermediary layer... leaving a subarachnoid space... Pia mater - Inner layer - Adheres to the surface of the brain'; cns_questions.txt Q1 key E (innermost→outermost = pia, arachnoid, dura)", "corrected": false }, { "t": "Cerebrospinal fluid (CSF) & choroid plexus", "d": "CSF is produced by the choroid plexus (ependymal cells lining the ventricles), flows from the ventricles into the subarachnoid space, and is reabsorbed into venous blood by arachnoid villi at the same rate it is made. Provides mechanical protection and maintains electrolyte balance. Blocked reabsorption → hydrocephalus.", "topic": "Protective elements of the CNS: meninges, CSF/ventricles/choroid plexus, and the blood-brain barrier", "citation": "CNS Study Notes 2025 'Cerebrospinal Fluid' (lines 118-139): choroid plexus 'line the ventricles... produce cerebrospinal fluid', 'Flows from ventricles to the subarachnoid space', 'absorbed back into the blood by special villi on the arachnoid membrane', 'Reabsorbed... at the same rate it is produced', 'Hydrocephalus... if reabsorption of CSF is blocked'", "corrected": false }, { "t": "Cells that produce CSF", "d": "Ependymal cells — the glial cells lining the ventricles that form the choroid plexus and secrete cerebrospinal fluid. (Not astrocytes, microglia or interneurons.)", "topic": "Protective elements of the CNS: meninges, CSF/ventricles/choroid plexus, and the blood-brain barrier", "citation": "CNS Study Notes 2025 'Glial Cells of the CNS' (line 70): 'Ependymal cells - Produce cerebrospinal fluid'; cns_questions.txt Q2 answer key C (Ependymal cells)", "corrected": false }, { "t": "Blood-brain barrier (BBB)", "d": "Tightly joined (poreless) CNS capillary endothelium that maintains a stable brain environment and blocks large/harmful molecules. Glucose needs carrier-mediated transport to cross; clinically, dopamine cannot cross so its precursor L-dopa is used to treat Parkinson's. Astrocytes help form the BBB.", "topic": "Protective elements of the CNS: meninges, CSF/ventricles/choroid plexus, and the blood-brain barrier", "citation": "CNS Study Notes 2025 'The Blood-brain Barrier' (lines 140-159): CNS capillaries 'tightly joined; no pores', glucose 'Specific transport system... (carrier-mediated transport)', 'dopamine cannot cross... smaller precursor molecules (L-dopa) must be used'; 'Glial Cells' line 57 astrocytes 'Form the blood brain barrier'; corroborated Vander 16e Ch6 (line 6452) 'blood-brain barrier is formed by astrocytes and the cells that line the smallest blood vessels'", "corrected": false }, { "t": "Five sensory receptor classes (by stimulus)", "d": "Chemoreceptors (chemical ligands, e.g. O₂, glucose), mechanoreceptors (pressure, vibration, sound, acceleration), thermoreceptors (temperature), photoreceptors (light), nociceptors (noxious/injurious stimuli). All are transducers converting stimulus energy into receptor potentials.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Types of Sensory Receptors' (lines 500-512): receptors are 'transducers', '5 major groups': chemoreceptors (oxygen/glucose), mechanoreceptors (pressure, vibration, gravity, acceleration, sound), thermoreceptors (temperature), photoreceptors (light), nociceptors (noxious stimuli); corroborated Vander 16e Ch7 (lines 324-326)", "corrected": false }, { "t": "Cutaneous somatosensory receptors", "d": "Meissner's corpuscle (light touch), Merkel's corpuscle (touch), free nerve endings (pain), Pacinian (lamellated) corpuscle (vibration & deep pressure), Ruffini corpuscle (warmth/skin stretch). (Exam: vibration & deep pressure = Pacinian corpuscle.)", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Receptors for somatic sensation' (lines 561-565): Meissner's (Light touch), Merkel's (Touch), Free nerve ending (Pain), Lamellated/Pacinian (Vibration and deep pressure), 'Ruffini corpuscle (Warmth/mechanoreceptors)'; cns_questions.txt Q8 key B (Pacinian = vibration/deep pressure). Vander 16e Ch7 (line 1294) lists Ruffini as 'slowly adapting mechanoreceptor, skin stretch'", "corrected": false }, { "t": "Four attributes of sensory coding", "d": "A stimulus is encoded by modality (type — set by which receptor/labelled-line is activated; processed in different brain regions), intensity, duration, and location. Together these preserve stimulus information once it enters the CNS.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Neural Encoding' (lines 523-553): '4 types of information are coded... sensory type or modality, intensity, duration, and location'; 'Different modalities are processed in different parts of the brain'; 'Labeled line codes - 1:1 association of a receptor to a sensation'", "corrected": false }, { "t": "Stimulus intensity coding", "d": "A stronger stimulus gives a larger receptor potential, encoded three ways: frequency code (higher action-potential firing rate), population code (more receptors/neurons recruited), and temporal-pattern code (firing pattern, e.g. bursts vs steady). More APs → more neurotransmitter release centrally.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Neural Encoding: Intensity' (lines 566-612): 'Frequency coding... higher rate of action potential generation'; 'Population coding... more sensory neurons are recruited'; 'Temporal pattern coding... bursts vs steady rate of firing'; 'Increased stimulus intensity leads to more neurotransmitter release'", "corrected": false }, { "t": "Tonic vs phasic receptors (adaptation)", "d": "Adaptation = decline in firing during a maintained stimulus. Tonic (slowly adapting) receptors fire throughout the stimulus (Merkel's, free nerve endings, Ruffini) — monitor sustained parameters. Phasic (rapidly adapting) receptors fire only at onset/change then switch off (Pacinian, Meissner's) — signal change.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Neural Encoding: Duration' (lines 619-635): 'Adaptation - a reduction in the response... in the continuous presence of a stimulus'; Tonic (slowly adapting) 'generate action potentials throughout the duration... Merkel's corpuscles, free neuron endings, Ruffini corpuscles'; Phasic (rapidly adapting) 'fire when they first receive a stimulus but cease firing... Pacinian corpuscles, Meissner's corpuscles'; corroborated Vander 16e Ch7 (lines 1286-1294)", "corrected": false }, { "t": "Receptive field & two-point discrimination", "d": "A receptive field is the body area one sensory neuron responds to: smaller fields = greater spatial acuity. Two-point discrimination depends on receptor density and field size — best on hands and face (high density), worst on abdomen and proximal limbs. Overlapping neighbouring fields helps localise a stimulus.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Neural Encoding: Location' (lines 645-670): 'Smaller receptive fields: greater precision'; 'Two-point discrimination: best on the hands and the face and worst on the abdomen and proximal parts of the limbs'; 'Overlapping stimulation between neighboring receptive fields provides general information about the location'; cns_questions.txt Q11 key D", "corrected": false }, { "t": "Lateral inhibition", "d": "A localisation mechanism in which an active sensory neuron suppresses its neighbours, focusing second-order firing onto the centre of the stimulus. Sharpens contrast and enhances spatial acuity so the location is perceived more precisely.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Neural Encoding: Location - Lateral inhibition' (lines 672-682): 'Lateral inhibition - to sharpen contrast by focusing the activation of the neurons on the centre of a stimulus... enhancing spatial acuity... suppressing signals from neighboring neurons... focuses second-order sensory afferent firing to the centre of the stimulus location'", "corrected": false }, { "t": "Sensory homunculus", "d": "A topographic body map in the somatosensory cortex (postcentral gyrus, parietal lobe). Cortical area is proportional to receptor density, not body size — face and hands occupy disproportionately large areas; abdomen and legs small. Maps show use-dependent plasticity.", "topic": "Sensory receptor types and neural encoding (modality, intensity, duration, location)", "citation": "CNS Study Notes 2025 'Topographical Organization' (lines 742-761): somatosensory cortex 'Located in the parietal lobe... postcentral gyrus'; 'Sensory homunculus - a topographic representation... Density of receptors for various parts of the body are not the same... face and hands is relatively large... abdomen, legs and feet is relatively small'; 'Plasticity - maps change according to usage'", "corrected": false }, { "t": "Basal nuclei (basal ganglia)", "d": "Large subcortical nuclei deep in the cerebral hemispheres (caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra). They (1) initiate movement and (2) suppress muscles that would resist the intended movement, via cortex→basal nuclei→thalamus→cortex loops. (Exam Q17: both A and C.)", "topic": "Basal nuclei (basal ganglia) and their role in movement", "citation": "CNS Study Notes 2025 'Basal Nuclei (Basal Ganglia)' (lines 920-932): 'collection of large nuclei deep within the cerebral hemispheres'; '5 basal nuclei (caudate, putamen, globus pallidus, subthalamic and substantia nigra)'; 'Initiate movement... Suppress the activity of muscles that would resist the intended movement'; cns_questions.txt Q17 key E ('A and C are correct'); corroborated Vander 16e Ch6 (line 5180)", "corrected": false }, { "t": "Basal nuclei & the extrapyramidal system", "d": "The basal nuclei are part of the extrapyramidal system, running looping parallel circuits (cortex→basal nuclei→thalamus→cortex) that modulate and refine movement, posture and tone. Dysfunction causes movement disorders (Parkinson's, Huntington's, dystonia) — rigidity/spasticity or flaccid paralysis depending on the pathway.", "topic": "Basal nuclei (basal ganglia) and their role in movement", "citation": "CNS Study Notes 2025 'Basal nuclei - extrapyramidal system' (lines 933-947): 'Part of the extrapyramidal system... modulate and refine movement... posture, and coordination'; 'looping parallel circuits... sensorimotor cortex to the basal nuclei, then to the thalamus, and finally back to the cortex'; 'hypercontracted muscles (rigidity, spasticity) or flaccid paralysis'; 'movement disorders like Parkinson's disease, Huntington's disease, and dystonia'", "corrected": false }, { "t": "Cerebellum", "d": "The 'little brain' under the cerebrum at the back of the brainstem. Coordinates movement using sensory input plus motor commands from cortex; provides motor timing, scaling and learning, coordinates agonist/antagonist and multi-joint movements, and controls balance, gait and eye movements. It influences movement indirectly (via brainstem nuclei and thalamus→cortex), not by directly driving motor neurons.", "topic": "Cerebellum", "citation": "CNS Study Notes 2025 'Cerebellum' (lines 283-294): 'Little brain... Located under the cerebrum at the back of the brainstem'; 'Motor timing, scaling, coordination & learning'; 'Balance and gait'; 'Eye movements'; and (lines 948-960) 'Influences posture and movement indirectly by means of input to brainstem nuclei and (by way of the thalamus) to regions of the sensorimotor cortex'; 'Timing of the agonist/antagonist components... Coordinate movements that involve several joints'", "corrected": false }, { "t": "Major divisions of the brain", "d": "Forebrain → cerebrum + diencephalon; midbrain (single division); hindbrain → cerebellum + pons + medulla oblongata. The brainstem = midbrain + pons + medulla. Three gross parts: cerebrum, cerebellum, brainstem. (Exam Q10: midbrain, pons & medulla are housed in the brainstem.)", "topic": "Functional brain divisions: cerebrum/cortical lobes, diencephalon (thalamus, hypothalamus), and brainstem subdivisions (midbrain/pons/medulla)", "citation": "CNS Study Notes 2025 'Major Divisions of the Human Brain' (lines 201-204): 'Forebrain develops into two major subdivisions: cerebrum and diencephalon'; 'Midbrain develops as a single major division'; 'Hindbrain develops into three parts: cerebellum, pons, medulla oblongata'; 'Brainstem: midbrain, pons, and medulla oblongata'; line 191 '3 main parts of the brain: cerebrum, cerebellum, brainstem'; cns_questions.txt Q10 key B", "corrected": false }, { "t": "Four cortical lobes & their functions", "d": "Frontal — personality, emotion, movement control; parietal — skin & muscle sensation; occipital — vision; temporal — hearing and memory. The left and right hemispheres are connected by the corpus callosum (a large nerve-fibre tract). (Exam Q13: hemispheres joined by the corpus callosum.)", "topic": "Functional brain divisions: cerebrum/cortical lobes, diencephalon (thalamus, hypothalamus), and brainstem subdivisions (midbrain/pons/medulla)", "citation": "CNS Study Notes 2025 'Main Divisions and Functions of the CNS' (lines 310-319): 'Frontal lobe - Personality, emotions and the control of movement'; 'Parietal lobe - Skin and muscle sensation'; 'Occipital lobe - Vision'; 'Temporal lobe - Hearing and memory functions'; 'Corpus callosum - Nerve axons that link the left and right hemispheres'; cns_questions.txt Q13 key B", "corrected": false }, { "t": "Thalamus vs hypothalamus", "d": "Both are diencephalon. Thalamus = relay station and integrating centre — nearly all sensory information passes through it en route to the cortex, and it can 'shape' that signal. Hypothalamus = key role in homeostasis and behavioural drives (and houses the posterior pituitary). (Exam Q5/Q7: hypothalamus → homeostasis/emotions.)", "topic": "Functional brain divisions: cerebrum/cortical lobes, diencephalon (thalamus, hypothalamus), and brainstem subdivisions (midbrain/pons/medulla)", "citation": "CNS Study Notes 2025 'Diencephalon' (lines 234-249): Thalamus 'Integrating center and relay station... almost all sensory information... is transmitted through the thalamus on its way to the cerebral cortex... can shape sensory information'; Hypothalamus 'important role in homeostasis and behavioral drives... Includes the posterior portion of the pituitary gland'; cns_questions.txt Q5 key D (emotions), Q7 key E (hypothalamus → homeostasis)", "corrected": false }, { "t": "Brainstem subdivisions", "d": "Midbrain — eye movements, visual/auditory processing; contains the substantia nigra (dopamine neurons). Pons — relays between cerebrum and cerebellum; helps coordinate breathing. Medulla oblongata — connects to spinal cord; houses autonomic centres for cardiovascular, respiratory and digestive control.", "topic": "Functional brain divisions: cerebrum/cortical lobes, diencephalon (thalamus, hypothalamus), and brainstem subdivisions (midbrain/pons/medulla)", "citation": "CNS Study Notes 2025 'Brainstem' (lines 254-272): Midbrain 'Eye movements, auditory and visual processing... Contains the substantia nigra... rich in dopamine neurons'; Pons 'Relay station between the cerebrum and cerebellum... Coordination of breathing'; Medulla oblongata 'Where the brainstem connects to the spinal cord... autonomic centers for regulation of visceral functions (cardiovascular, respiratory and digestive control)'", "corrected": false }, { "t": "Neurodegenerative diseases (overview)", "d": "Progressive loss of neuron structure and function; the strongest risk factor is increasing age. Key examples: Alzheimer's (dementia), Parkinson's (movement; substantia nigra dopamine loss), ALS (motoneuron loss, sparing eye muscles & sphincters), Huntington's (movement; striatal neuron loss).", "topic": "Neurodegenerative diseases (Parkinson's, Alzheimer's, ALS, Huntington's)", "citation": "CNS Study Notes 2025 'Neurodegenerative Diseases' (lines 1294-1305): 'progressive loss of structure and function of neurons'; 'Most consistent risk factor... increasing AGE'; Alzheimer's (dementia), Parkinson's ('dopaminergic neurons in substantia nigra'), ALS ('loss of motoneurons (except for eye muscles and sphincters)'), Huntington's ('movement disorder from loss of... neurons in striatum')", "corrected": false }, { "t": "Alzheimer's disease — neuropathology", "d": "Commonest cause of dementia. Hallmarks: senile (amyloid) plaques — extracellular β-amyloid (Aβ) deposits between neurons; neurofibrillary tangles — intracellular hyperphosphorylated tau; and synaptic loss. Cholinergic hypothesis: loss of cholinergic neurons (basal forebrain, hippocampus, frontal/parietal cortex), with Aβ reducing ACh.", "topic": "Neurodegenerative diseases (Parkinson's, Alzheimer's, ALS, Huntington's)", "citation": "CNS Study Notes 2025 'Alzheimer's Disease / Neuropathology / Cholinergic Hypothesis' (lines 1315-1343): 'Primary neurodegenerative cause of dementia'; 'Senile (amyloid) plaques: Extracellular deposits of beta-amyloid protein (Aβ)... between nerve cells'; 'Neurofibrillary tangles: Tangles of hyperphosphorylated tau protein accumulated inside the neuron'; 'Synaptic loss'; cholinergic hypothesis 'loss of cholinergic neurons... basal forebrain, hippocampus, frontal and parietal cortex... β-amyloid... reduction in choline uptake and release of ACh'", "corrected": false }, { "t": "Parkinson's disease", "d": "Degeneration of dopaminergic neurons in the substantia nigra pars compacta (basal nuclei), disrupting voluntary motor control. Symptoms appear after 60-70% are lost: bradykinesia, resting tremor, rigidity, postural instability, shuffling gait. Treated with L-dopa (crosses the BBB, unlike dopamine) → converted to dopamine; deep brain stimulation is an alternative.", "topic": "Neurodegenerative diseases (Parkinson's, Alzheimer's, ALS, Huntington's)", "citation": "CNS Study Notes 2025 'Parkinson's Disease / Treatment' (lines 1354-1389): 'neurons in the substantia nigra pars compacta (SNpc) of basal nuclei... Pars compacta... contains dark dopamine containing neurons... disrupts voluntary motor control'; symptoms bradykinesia, asymmetric resting tremor, rigidity, postural instability, shuffling steps; 'Symptoms of PD appear after 60-70% of dopaminergic neurons in SNpc are lost'; 'Dopamine cannot cross the blood-brain barrier but L-Dopa can'; 'Deep brain stimulation (DBS) - Alternate treatment'", "corrected": false }, { "t": "Pyramidal vs extrapyramidal motor systems", "d": "Pyramidal system = corticospinal tract (passes through the medullary pyramids; voluntary limb/body movement) + corticobulbar tract (to brainstem cranial-nerve nuclei; head/face/tongue/neck). Extrapyramidal system = brainstem pathways that bypass the pyramids and largely stay uncrossed — controlling posture, tone, balance and locomotion.", "topic": "Motor system organization: pyramidal vs extrapyramidal systems, corticobulbar tract, UMN vs LMN, motor hierarchy/homunculus", "citation": "CNS Study Notes 2025 'Corticospinal Tract' (lines 1013-1033): CST 'pass through the pyramids of the medulla... voluntary or willed and skilled movements... synapse onto alpha motor neurons that control the distal muscles'; 'Corticobulbar Tract' (lines 1034-1050): CBT 'ends in brainstem... synapse in nuclei... cell bodies of the cranial neurons... Voluntary control of movements of muscles of the head, face, tongue, neck'; 'Brainstem Pathways' (lines 1051-1064) extrapyramidal 'Do not pass through the medullary pyramids... remain uncrossed... posture... locomotion'", "corrected": false }, { "t": "Upper vs lower motor neurons", "d": "Descending motor pathways are a 2-neuron chain. Upper motor neurons (UMNs) originate in the primary motor cortex (pyramidal) or brainstem nuclei (extrapyramidal) and run down descending tracts. Lower motor neurons (LMNs) — e.g. alpha motoneurons in the ventral horn — receive UMN input and directly innervate skeletal muscle.", "topic": "Motor system organization: pyramidal vs extrapyramidal systems, corticobulbar tract, UMN vs LMN, motor hierarchy/homunculus", "citation": "CNS Study Notes 2025 'Descending Pathways - UMNs & LMNs' (lines 985-999): 'Generally follow a 2-neuron chain... Upper Motor Neurons (UMNs)... Originate in the primary motor cortex (pyramidal system) or brainstem nuclei (extrapyramidal system)... Send signals down descending tracts'; 'Lower Motor Neurons (LMNs)... Originate in the ventral horn of the spinal cord or cranial nerve nuclei... Directly innervate skeletal muscles'", "corrected": false }, { "t": "Corticospinal connection to motoneurons", "d": "~90% of corticospinal fibres cross to the contralateral side at the brainstem; below this, CST axons make monosynaptic connections directly onto alpha motoneurons that activate (distal) muscles — only one synapse from muscle. (Exam Q16: monosynaptic; alpha.)", "topic": "Motor system organization: pyramidal vs extrapyramidal systems, corticobulbar tract, UMN vs LMN, motor hierarchy/homunculus", "citation": "CNS Study Notes 2025 'Corticospinal Tract' (lines 1026-1033): '~90% of the CST crosses to the contralateral side of the nervous system at the brainstem level'; 'CST axons synapse onto alpha motor neurons that control the distal muscles'; 'CST neurons are only one neuronal synapse away from muscles'; cns_questions.txt Q16 key A (Monosynaptic; alpha)", "corrected": false }, { "t": "Long-term potentiation (LTP)", "d": "Frequently used synapses grow stronger over time — the proposed cellular basis of learning and memory. Occurs at glutamatergic synapses via AMPA and NMDA receptors; intense firing triggers structural/chemical changes (e.g. more postsynaptic receptors) that enhance future responsiveness. An example of neural plasticity.", "topic": "Mechanism of memory formation: long-term potentiation (LTP), neural plasticity, glutamate/AMPA/NMDA receptors", "citation": "CNS Study Notes 2025 'Model for Memory Formation / LTP at Glutaminergic Synapses' (lines 1230-1251): 'LTP... frequently used synapses increase in effectiveness over time'; 'Glutamate is the most common excitatory neurotransmitter'; 'AMPA receptors... NMDA receptors... key role in long-term potentiation'; 'structural changes in synapses, such as more receptors on the postsynaptic membrane'; 'LTP is the fundamental mechanism behind learning and memory'; corroborated Vander 16e Ch8 (lines 1947-1961)", "corrected": false }, { "t": "Limbic system", "d": "An interconnected group of structures driving emotion, motivation and survival behaviours (feeding, reproduction, fight-or-flight) and integrating learning and visceral/endocrine function. Primary components: thalamus, hypothalamus, basal ganglia, cingulate gyrus, hippocampus and amygdala.", "topic": "Limbic system (components and functions)", "citation": "CNS Study Notes 2025 'Functions of the Limbic System' (lines 297-307): 'interconnected group of brain structures... behavioural and emotional responses... feeding, reproduction... fight or flight... Learning, emotion... visceral functions... integration of endocrine function'; 'Primary components: Thalamus, hypothalamus, basal ganglia, cingulate gyrus, hippocampus, amygdala'; corroborated Vander 16e Ch6 (lines 5190-5191)", "corrected": false } ], "cardio": [ { "t": "Four heart valves", "d": "Two atrioventricular (AV) valves between atria and ventricles — tricuspid (right) and bicuspid/mitral (left); two semilunar (arterial) valves between ventricles and arteries — pulmonary (right) and aortic (left). All ensure one-way blood flow", "topic": "Heart valves and valve function", "citation": "Study Notes L301-313: 'Atrioventricular (AV) valves... AV valve located between the left atrium and left ventricle is the bicuspid or mitral valve... right atrium and the right ventricle is the tricuspid valve. Semilunar (arterial) valves... Valve between the left ventricle and the aorta is the aortic valve... right ventricle and the pulmonary trunk is the pulmonary valve'; L326 'Ensure unidirectional flow of blood'", "corrected": false }, { "t": "How heart valves open and close", "d": "Passively, driven only by pressure gradients across the valve — no muscle contraction or energy expended. A forward pressure gradient opens a one-way valve; a backward gradient closes it", "topic": "Heart valves and valve function", "citation": "Study Notes L329-333: 'The valves open and close passively due to differences in pressure or pressure gradients... Energy is not expended to open or close a valve... Valves do not require muscles to open or close them... A forward pressure gradient opens a one way valve; a backwards pressure gradient closes a one-way valve'", "corrected": false }, { "t": "AV valve apparatus (chordae tendineae & papillary muscles)", "d": "Leaflet edges attach via fibrous chordae tendineae to papillary muscles projecting from the ventricular wall. When the ventricle contracts the papillary muscles pull the chordae taut, holding the AV valve shut and preventing it from everting into the atrium — they do NOT open or close the valve", "topic": "Heart valves and valve function", "citation": "Study Notes L353-390: 'chordae tendineae extend from the edges of the leaflets and attach to papillary muscles... Papillary muscles → cone shaped muscles that protrude from the inner surface of the ventricular walls... Pulling of the chordae tendineae by the papillary muscles keeps the AV valve in a closed position... keeps the AV valves from everting... contraction of the papillary muscles does not open or close the valves'; FAQ Q4", "corrected": false }, { "t": "Semilunar vs AV valves", "d": "Semilunar (aortic, pulmonary) valves have 3 cusps and NO chordae tendineae/papillary muscles — the artery doesn't contract, so back-pressure can't evert them. AV valves (tricuspid, bicuspid) require the chordae/papillary apparatus to withstand the high backward pressure of ventricular contraction", "topic": "Heart valves and valve function", "citation": "Study Notes L396-408: '3 leaflets or cusps... Do not have chordae tendineae or papillary muscles... The pressure pushing back against the valve from the artery is not high enough to force the valve to evert or open backwards into the ventricle, as the artery does not contract'; FAQ Q16 L228-250", "corrected": false }, { "t": "Cardiac conduction sequence", "d": "SA node → internodal pathways (→ atrial contraction) → AV node → bundle of His → left & right bundle branches (down interventricular septum) → Purkinje fibres → ventricular myocardium. Atria depolarise/contract as a unit before the ventricles do", "topic": "Conduction system beyond SA node", "citation": "Study Notes L613-627 'Summary: Conducting System'; Sample Q13 answer key C (SA node-AV node-AV bundle-Bundle branches-Purkinje fibers). Note: order is SA→AV node→bundle of His(AV bundle)→bundle branches→Purkinje, which the card states correctly", "corrected": false }, { "t": "AV nodal delay", "d": "Conduction through the AV node is slow, taking ~0.1 s (100 ms). This delay lets the atria finish depolarising and contracting — filling the ventricles — before the ventricles are excited and contract", "topic": "Conduction system beyond SA node", "citation": "Study Notes L589-596: 'takes ~ 100 milliseconds for the stimulus to pass through the AVN to the Bundle of His... This delay ensures that the atria depolarize and contract before the ventricles depolarize and contract'; Vander 16e Ch12 L1525-1526 'AV node is relatively slow (requiring approximately 0.1 sec). This delay allows atrial contraction to be completed before ventricular excitation'; Sample Q2 key C", "corrected": false }, { "t": "AV node & bundle of His as sole AV connection", "d": "The non-conducting cardiac (fibrous) skeleton electrically insulates the atria from the ventricles; the AV node + bundle of His are the ONLY normal electrical pathway between them. (Note: Purkinje fibres distribute the impulse within the ventricles, but are not the atria–ventricle link)", "topic": "Conduction system beyond SA node", "citation": "Study Notes L566-570 & L598: 'Non-conducting... Physically separates the atria from the ventricles... The only electrical connection between the atria and ventricles in a normal heart is the AVN and the Bundle of His'; Sample Q17 (key E; option D 'Purkinje fibers are the only electrical connection' is the distractor)", "corrected": false }, { "t": "Purkinje fibres", "d": "Terminal conducting myocytes with fast conduction velocity and diffuse distribution throughout the ventricles, so the left and right ventricular myocytes depolarise and contract almost simultaneously; they pass the impulse to contractile cells via gap junctions", "topic": "Conduction system beyond SA node", "citation": "Study Notes L602-606: 'Purkinje fibers... Large number, diffuse distribution (ie. all over the ventricles), fast conduction velocity... Stimulus depolarized left and right ventricular myocytes and causes contraction nearly simultaneously'; Sample Q17 key E 'Purkinje fibers transmit action potentials to the ventricular myocardium by gap junctions'", "corrected": false }, { "t": "Stroke volume — three determinants", "d": "SV = EDV − ESV, governed by (1) end-diastolic volume / preload, (2) myocardial contractility, and (3) afterload. Raising preload or contractility increases SV; raising afterload decreases SV", "topic": "Determinants of stroke volume", "citation": "Study Notes L15 'SV = EDV - ESV'; L1365-1367 '3 factors that affect the stroke volume: 1) the end diastolic volume (EDV), also called the preload, 2) the contractility of the ventricular myocardium, and 3) the afterload'; L1474 'As afterload increases, SV decreases'; L1435-1436 (increased sympathetic/contractility increases SV)", "corrected": false }, { "t": "Preload (EDV)", "d": "The load/stretch on the ventricular myocardium just before contraction — i.e. the end-diastolic volume, the blood in the ventricle after filling. Increased venous return raises EDV/preload, stretching the fibres and increasing the force of contraction", "topic": "Determinants of stroke volume", "citation": "Study Notes L1389-1391: 'Preload → the tension or load on the ventricular myocardium before it begins to contract, or the amount of filling of the ventricles at the end of diastole, which is the EDV'; L1385-1388 'Increase the venous return... will more fully fill the ventricles with blood, increasing the EDV, increasing SV'", "corrected": false }, { "t": "Frank-Starling mechanism", "d": "An intrinsic length–tension relationship (independent of nerves/hormones): the greater the EDV (sarcomere stretch), the more forcefully the ventricle contracts, so SV rises. It matches the outputs of the two ventricles so blood doesn't pool in one circuit", "topic": "Determinants of stroke volume", "citation": "Study Notes L1399-1417: 'Frank-Starling mechanism... Intrinsic mechanism... Occurs independent of neural or hormonal stimulation... As you increase EDV, you increase SV... The Frank-Starling mechanism is a length-tension curve... matches the outputs of the two ventricles... blood does not accumulate in one circuit'; Vander 16e Ch12 L3161-3265", "corrected": false }, { "t": "Contractility", "d": "The strength of ventricular contraction at any given EDV. Sympathetic stimulation increases contractility (via a G-protein/phosphorylation mechanism), raising SV and ejection fraction at the same EDV; the ventricles get little/no parasympathetic input, so vagal activity does not change ventricular contractility", "topic": "Determinants of stroke volume", "citation": "Study Notes L1432-1462: 'contractility = the strength of contraction at any given EDV... Increased sympathetic stimulation will increase the strength of contraction... Altering parasympathetic activity will not affect contractility of the ventricles... receives little or no parasympathetic innervation... Sympathetic regulation of myocardial contractility acts through a G protein coupled mechanism... phosphorylated by intracellular kinases'", "corrected": false }, { "t": "Afterload", "d": "The load/tension the ventricle must overcome to open the semilunar valves and eject blood — closely tied to arterial pressure. Higher afterload (high BP, raised vascular resistance, a stenotic valve) lengthens isovolumetric contraction and decreases SV", "topic": "Determinants of stroke volume", "citation": "Study Notes L1465-1477: 'Afterload → the tension against which the ventricle must eject its blood; it is closely related to the arterial pressure... The greater the afterload, the longer the period of isovolumetric contraction... and a smaller stroke volume... As afterload increases, SV decreases... Arterial blood pressure, vascular resistance, stenotic valve'; Vander 16e Ch12 L3618", "corrected": false }, { "t": "Ejection fraction", "d": "EF = SV / EDV; the fraction of end-diastolic volume ejected per beat, normally ~50–75% at rest. Increased contractility (sympathetic stimulation) empties the ventricle more completely and raises EF", "topic": "Determinants of stroke volume", "citation": "Study Notes L14 'EF (ejection fraction) = SV/EDV'; L1430-1448 'the ejection fraction of the ventricles is between 50 - 75%... Increased contractility will lead to a more complete ejection of the blood, increasing the ejection fraction'; Vander 16e Ch12 L3267-3269 'ejection fraction averages between 50% and 75% under resting conditions... Increased contractility causes an increased ejection fraction'", "corrected": false }, { "t": "Arterioles as resistance vessels", "d": "Arterioles are ringed by circular smooth muscle and have a small radius, making them the major site of resistance in the systemic circuit; the largest drop in MAP occurs across them. Adjusting their diameter regulates both blood-flow distribution to organs and overall MAP", "topic": "Control of arteriolar resistance", "citation": "Study Notes L1522-1545: 'Walls of arterioles have an abundance of circular smooth muscle that forms rings around the arterioles... small enough radius to offer considerable resistance to blood flow and are called resistance vessels'; L2018 'The largest drop in pressure occurs at the level of the arterioles'; L1542-1546 (distribution + MAP)", "corrected": false }, { "t": "Extrinsic control of arteriolar resistance", "d": "Whole-body controls acting via nerves/hormones on top of intrinsic basal tone: sympathetic fibres release norepinephrine causing vasoconstriction and discharge at a baseline 'sympathetic tone' (raised → vasoconstriction, lowered → vasodilation); adrenal epinephrine and NO-releasing (noncholinergic, nonadrenergic) neurons also modulate tone. This is the main route for regulating MAP", "topic": "Control of arteriolar resistance", "citation": "Study Notes L1560-1584: 'sympathetic nerve fibers release norepinephrine to cause vasoconstriction... discharge at some basal level called sympathetic tone... Sympathetic tone can be increased, causing further vasoconstriction, or decreased, causing vasodilation... Noncholinergic, nonadrenergic neurons... Release nitric oxide, a vasodilator... Hormone: epinephrine... Released from the adrenal medulla'", "corrected": false }, { "t": "Active hyperemia", "d": "A local (intrinsic) control: when an organ's metabolic activity rises, local chemical changes (↓O₂, ↑CO₂, ↓pH, metabolites) act directly on arteriolar smooth muscle to cause vasodilation, increasing blood flow to match demand — no nerves or hormones involved", "topic": "Control of arteriolar resistance", "citation": "Study Notes L1592-1602: 'Active hyperemia → local control which acts to increase blood flow when the metabolic activity of an organ or tissue increases... Arteriolar smooth muscle is sensitive to local chemical changes in the extracellular fluid... oxygen or carbon dioxide levels or pH... cause vasodilation and increase blood flow... Does not involve any nerves or hormones'", "corrected": false }, { "t": "Flow autoregulation & myogenic response", "d": "Local mechanisms (at constant metabolic rate) that keep organ blood flow stable when arterial pressure changes. A pressure rise washes out metabolites/raises O₂ (chemical) and stretches the vessel wall — the myogenic response, in which arteriolar smooth muscle contracts to stretch — both constricting arterioles to return flow toward normal", "topic": "Control of arteriolar resistance", "citation": "Study Notes L1604-1637: 'Flow autoregulation... a change in its blood supply resulting from a change in blood pressure... Occurs at a constant metabolic activity... Myogenic response → the direct response of arteriolar smooth muscle to stretch... Arteriolar smooth muscle responds to this stretch by contracting... increase in oxygen levels and a decrease in metabolites... also act to constrict the arteriolar smooth muscle'", "corrected": false }, { "t": "Coronary circulation", "d": "Branches of the aorta (from the aortic sinus) supplying the myocardium; cardiac veins drain into the coronary sinus, which empties deoxygenated blood into the right atrium. The heart's nutrients come from this circulation, NOT from blood inside the chambers", "topic": "Coronary circulation & CAD", "citation": "Study Notes L435-447: 'receives its blood supply through arteries that branch from the aorta... Aortic sinus is a dilation or out-pocketing of the ascending aorta; site where the left and right coronary arteries [arise]... Cardiac veins → collect poorly oxygenated blood and empty into the coronary sinus, which returns blood to the right atrium'; Sample Q16 key A (source of nutrients = coronary circulation, not blood in chambers)", "corrected": false }, { "t": "Coronary blood flow timing", "d": "Myocardial blood flow is not steady — it nearly ceases during systole (contracting myocardium compresses the vessels) and peaks during diastole when the heart is relaxed", "topic": "Coronary circulation & CAD", "citation": "Study Notes L452-454: 'Myocardial blood flow is not steady: Blood flow almost ceases while the heart is contracted (systole) and peaks while the heart is relaxed (diastole)'; Sample Q18 key E 'Myocardial blood flow is maximal during ventricular diastole'", "corrected": false }, { "t": "Coronary artery disease (angina vs MI)", "d": "Atherosclerosis narrows the coronary arteries with plaque (fat, cholesterol, calcium), reducing myocardial flow. Restricted flow causes angina (chest pain); complete blockage causes myocardial infarction (heart attack), in which heart muscle dies from loss of blood supply", "topic": "Coronary circulation & CAD", "citation": "Study Notes L456-471: 'Caused by atherosclerosis of the coronary arteries... arteries become hardened and narrowed because of an excessive accumulation of plaque... Atherosclerotic plaque → made of fat, cholesterol, calcium and other substances... Angina → chest pain... Myocardial infarction → heart attack... heart muscle dies due to loss of blood supply'", "corrected": false }, { "t": "Three capillary types", "d": "Continuous (complete endothelium, tight junctions though often with intercellular clefts; lowest permeability; most tissues), fenestrated (pores/fenestrae; more permeable; kidneys, GI tract, endocrine organs, choroid plexus), and sinusoidal/discontinuous (large fenestrae + intercellular gaps, thin/absent basement membrane; most permeable; only in liver, bone marrow, spleen)", "topic": "Three capillary types", "citation": "Study Notes L1662-1705: 'continuous capillary, fenestrated capillary, sinusoidal capillary... Continuous... Uninterrupted/complete endothelium... Tight junctions between adjacent endothelial cells... Have the lowest permeability of all capillary types... Fenestrated... Found in... endocrine organs, the choroid plexus, the GI tract and the kidneys... Sinusoids... Found only in liver, bone marrow and spleen'; Sample Q6 & Q20", "corrected": true }, { "t": "Sinusoidal capillaries", "d": "Discontinuous capillaries with wide irregular lumens, very large fenestrae, large interendothelial gaps and a thin/absent basement membrane — the MOST permeable type. They allow whole red blood cells and plasma proteins to cross, and are found only in liver, bone marrow, and spleen (often with phagocytic cells in the lining)", "topic": "Three capillary types", "citation": "Study Notes L1698-1705: 'Sinusoids... Large diameter, flattened and irregularly shaped... Called discontinuous capillaries... Have very large fenestrae and large gaps between adjacent endothelial cells... Basement membrane very thin or absent... Allow the free exchange of water and solutes, including large substances such as red blood cells, cell debris, and plasma proteins... Found only in liver, bone marrow and spleen'; Sample Q6 key B confirms they are NOT the least permeable; Q6 option e confirms phagocytic cells in lining", "corrected": false }, { "t": "Veins as capacitance (reservoir) vessels", "d": "At rest ~60% of total blood volume sits in the venous system. Veins are highly distensible, high-capacitance vessels that expand at low pressure with little recoil, acting as a blood reservoir; sympathetic-driven venoconstriction shifts this blood toward the heart", "topic": "Venous system & venous return", "citation": "Study Notes L1878-1898: 'At rest, ~ 60% of the blood volume is found in the venous system... High capacitance vessels as can store large amounts of blood... Highly distensible, expanding easily at low pressures and have little elastic recoil... Reservoir for blood'; L1897-1899 'Smooth muscle in veins... Innervated by sympathetic neurons which cause contraction... to increase pressure'", "corrected": false }, { "t": "Mechanisms of venous return", "d": "Three mechanisms raise venous pressure to drive blood back to the heart: sympathetic venoconstriction of venous smooth muscle, the skeletal-muscle pump (contractions compress veins), and the respiratory pump (inspiration). Venous valves keep this flow one-way. Increased venous return raises EDV, engaging the Frank-Starling mechanism", "topic": "Venous system & venous return", "citation": "Study Notes L1896-1912: 'Smooth muscle in veins... sympathetic neurons which cause contraction... Skeletal muscle pump... Compresses veins... Venous pressure increases... Respiratory pump... Inspiration causes an increase in venous return... Increased venous return to the heart will increase the end-diastolic volume... now we have the Frank Starling mechanism'; L1887-1889 venous valves ensure one-way flow", "corrected": false }, { "t": "First & second heart sounds", "d": "S1 ('lub') is produced by closure of the AV valves at the start of isovolumetric ventricular contraction, marking the onset of systole; S2 ('dub') is produced by closure of the semilunar valves, marking the onset of diastole. The sounds reflect turbulence as the valves snap shut", "topic": "Heart sounds and murmurs", "citation": "Study Notes L1203-1207: 'First heart sound → lub; caused by closure of the AV valves at the beginning of isovolumetric ventricular contraction and signifies the onset of ventricular systole. Second heart sound → dub; caused by closure of the semilunar valves and signifies the onset of ventricular diastole. The heart sounds reflect turbulence when the valves passively snap shut'", "corrected": false }, { "t": "Heart murmurs (stenotic vs insufficient valves)", "d": "Normal blood flow is laminar and silent; turbulent flow makes a sound called a murmur. A stenotic valve fails to open fully (stiff/calcified leaflets) so forward flow becomes turbulent; an insufficient (incompetent) valve fails to close fully so blood leaks backward — both produce murmurs", "topic": "Heart sounds and murmurs", "citation": "Study Notes L1214-1231: 'Normally blood flow through valves and vessels is laminar flow and makes no sound... Turbulent flow makes a sound and is called a murmur. Stenotic valve → a valve in which the leaflets do not open completely... stiffer due to calcium deposits or scaring... becomes turbulent... Insufficient valve → does not close completely... blood flows backwards through the leaky valve and produces turbulence'", "corrected": false }, { "t": "Autonomic control of heart rate", "d": "The SA node sets HR; the ANS modulates it. Sympathetic stimulation (norepinephrine, plus adrenal epinephrine) increases the slope of the pacemaker potential (↑F-type Na⁺ and T-type Ca²⁺ permeability), reaching threshold faster → ↑HR. Parasympathetic (vagal ACh) decreases the slope → ↓HR. At rest, parasympathetic tone dominates", "topic": "Autonomic control of HR & contractility", "citation": "Study Notes L1302-1339: 'Under resting conditions, parasympathetic effects dominate for heart rate... Sympathetic stimulation of the SAN → increases the slope of the pacemaker potential... by increasing the permeability of the F-type and T-type channels... F-type channels allow Na+ to enter... T-type channels allow Ca2+ to enter... Parasympathetic stimulation... decreases the slope'; L1304-1305 (epinephrine from adrenal medulla); L1349-1350", "corrected": false }, { "t": "Autonomic effects on AV conduction & contractility", "d": "Sympathetic stimulation speeds AV-nodal conduction (shorter AV delay) and increases contractility of atrial AND ventricular myocardium. Parasympathetic stimulation slows AV conduction (longer AV delay) and decreases atrial contractility only — the ventricles get little/no vagal innervation, so vagal activity does not change ventricular contractility", "topic": "Autonomic control of HR & contractility", "citation": "Study Notes L1250-1269: 'Parasympathetic... Decrease the conduction... through the AVN, increasing AV nodal delay... Decrease contractility of the atrial myocardium... parasympathetic stimulation has no effect on contractility of the ventricle. Sympathetic... Increase conduction... through the AVN, decreasing AV nodal delay... Increase the contractility of the atrial and ventricular myocardium'", "corrected": false }, { "t": "MAP = CO × TPR", "d": "Mean arterial pressure is the product of cardiac output and total peripheral resistance. TPR is the combined resistance of all systemic vessels, determined primarily by arteriolar resistance; thus changes in arteriolar diameter are the chief way TPR (and MAP) are adjusted", "topic": "MAP = CO × TPR and TPR", "citation": "Study Notes L17 'MAP = CO x TPR'; L2033-2048 'MAP = CO x TPR... TPR is the combined resistance to flow of all the systemic blood vessels... Major site of resistance in the systemic circuit → arterioles... Changes in TPR are due primarily to changes in the resistance of the arterioles... TPR is determined primarily by total arteriolar resistance'", "corrected": false } ], "ss": [ { "t": "Five cutaneous mechanoreceptors (adaptation)", "d": "Meissner's corpuscle = touch/pressure, rapidly adapting; Merkel's corpuscle = touch/pressure, slowly adapting; Pacinian corpuscle = vibration/deep pressure, rapidly adapting; Ruffini corpuscle = skin stretch, slowly adapting; free nerve endings = pain/temperature/touch (nociceptors, thermoreceptors, mechanoreceptors), slowly adapting.", "topic": "Cutaneous somatosensory receptor types (Meissner, Merkel, free nerve endings, Pacinian, Ruffini)", "citation": "Study Notes - Special Senses Physiology.txt L54-68: 'Meissner's corpuscles -> rapidly adapting mechanoreceptors; Merkel's corpuscles -> slowly adapting mechanoreceptors; Free neuron ending... nociceptors... thermoreceptors... mechanoreceptors; slowly adapting; Pacinian corpuscle -> responds to vibration and deep pressure; rapidly adapting; Ruffini corpuscle -> responds to skin stretch; slowly adapting'; Sample SS questions Q1 answer A (Meissner's = rapidly adapting)", "corrected": false }, { "t": "Rapidly vs slowly adapting receptors", "d": "Rapidly adapting receptors (Meissner's, Pacinian) fire mainly at stimulus onset/offset and filter out constant, unimportant stimuli (e.g. clothing on skin); slowly adapting receptors (Merkel's, Ruffini, free nerve endings) generate a persistent or slowly-decaying response for the entire duration of the stimulus.", "topic": "Cutaneous somatosensory receptor types (Meissner, Merkel, free nerve endings, Pacinian, Ruffini)", "citation": "Study Notes - Special Senses Physiology.txt L193-215: rapidly adapting receptor 'immediately generates a receptor potential... then quickly decays'; action potentials only at on/off; 'Rapidly adapting mechanoreceptors filter the unimportant information out... when you put a shirt on... but do not continually provide information all day'; L181-192 slowly adapting Merkel's 'remains on during the entire time the stimulus is occurring'; Sample SS questions Q12 answer D", "corrected": false }, { "t": "Three factors for stimulus localization", "d": "Receptive-field size (smaller field = finer localization), density of innervation (more receptors per area = better localization), and overlapping receptive fields (the brain compares relative firing frequencies of adjacent neurons to compute the exact site). Lateral inhibition further sharpens the estimate.", "topic": "Stimulus localization mechanisms (receptive-field size, density of innervation, overlapping receptive fields)", "citation": "Study Notes - Special Senses Physiology.txt L229-230: '3 important factors that affect our ability to localize a stimulus are: the receptive field size, the density of innervations, and overlapping receptive fields'; L244-245 'smaller receptive field allows for better localization'; L286-288 overlapping fields let brain compute site from relative activation; L289-291 lateral inhibition helps identify specific site", "corrected": false }, { "t": "Two-point discrimination (lips vs back)", "d": "The ability to perceive two nearby points as separate. High where receptors are small and densely packed with small receptive fields (lips, fingertips); poor where receptive fields are large and sparse (back), so two forceps tips activate only one sensory neuron and feel like a single point.", "topic": "Stimulus localization mechanisms (receptive-field size, density of innervation, overlapping receptive fields)", "citation": "Study Notes - Special Senses Physiology.txt L251-264: 'Lips have very densely packed sensory receptors, each with a fairly small receptive field... two tips of the forceps... activates two different sensory receptors... If the skin on our back is poked by the 2 tips of a forceps, only one sensory neuron is activated as there is a large receptive field... unable to identify that we are being poked with two different tips'; corroborated Vander 16e ch7 L520, L552-556", "corrected": false }, { "t": "Lateral inhibition", "d": "Sharpens stimulus localization and contrast: the strongly-stimulated central afferent (B) activates inhibitory interneurons that release glycine/GABA onto flanking afferents (A and C), suppressing their weaker signals far more than they inhibit B. This enhances the centre-vs-periphery contrast so the brain pinpoints the site. Operates in somatosensation and vision, NOT the auditory system.", "topic": "Lateral inhibition", "citation": "Study Notes - Special Senses Physiology.txt L293-324: 'Occurs in certain sensory systems such as somatosensation and vision; not important in the auditory system... inhibitory interneurons... release an inhibitory neurotransmitter (glycine or GABA) onto sensory neuron A and sensory neuron C... inhibition of the surrounding sensory neurons, A and C, is much greater than the neuron that is actually stimulated'; corroborated Vander 16e ch7 L651-718", "corrected": false }, { "t": "Anterolateral (spinothalamic) tract", "d": "Carries pain and temperature (from free nerve endings). First synapse is in the dorsal horn on the SAME side as the stimulus; the second-order neuron crosses (decussates) immediately in the spinal cord, ascends contralaterally, and synapses in the thalamus before projecting to the somatosensory cortex.", "topic": "Ascending somatosensory pathways: anterolateral (spinothalamic) vs dorsal column system, and where each decussates", "citation": "Study Notes - Special Senses Physiology.txt L376-395: 'First synapse is located in the dorsal horn of the grey matter of spinal cord on same side of body which was stimulated... Secondary neuron crosses over to the other side of the CNS at the level of the spinal cord... synapses with projection neuron in the thalamus which travels to somatosensory cortex... Painful information crosses immediately'; corroborated Vander 16e ch7 L1755-1760", "corrected": false }, { "t": "Dorsal column system", "d": "Carries fine touch and mechanoreception. The first-order sensory neuron ascends IPSILATERALLY up the spinal cord and makes its first synapse in the brainstem; the second-order neuron then crosses (decussates) at the level of the brainstem and synapses in the thalamus en route to the somatosensory cortex.", "topic": "Ascending somatosensory pathways: anterolateral (spinothalamic) vs dorsal column system, and where each decussates", "citation": "Study Notes - Special Senses Physiology.txt L397-415: 'sensory neuron ascends up to the brainstem on the same side... First synapse between the sensory neuron and the secondary neuron is in the brainstem... Secondary neuron crosses over to the other side of the CNS at the level of the brainstem... synapses with projection neuron in the thalamus... Touch information travels up the spinal cord on the same side'; corroborated Vander 16e ch7 L1763-1768", "corrected": false }, { "t": "Where each somatosensory pathway decussates", "d": "Both end in the contralateral somatosensory cortex, but cross at different levels: anterolateral/spinothalamic (pain & temperature) crosses immediately in the spinal cord; dorsal column (fine touch) ascends on the same side and crosses at the brainstem. (Key high-yield distinction.)", "topic": "Ascending somatosensory pathways: anterolateral (spinothalamic) vs dorsal column system, and where each decussates", "citation": "Study Notes - Special Senses Physiology.txt L416-419: 'Both pathways end in the somatosensory cortex on the contralateral side of the body... One pathway crosses right away (anterolateral system) and the other one ascends on the same side as the stimulus and then crosses at the level of the brainstem (dorsal column system)'; corroborated Vander 16e ch7 L1769-1773", "corrected": false }, { "t": "Refraction and the cornea", "d": "Refraction = bending of light as it passes from a less dense medium (air) to a denser one (the eyeball). The CORNEA is the structure primarily responsible for refraction; the lens then changes shape to fine-tune focus onto the retina. Too much or too little refraction reconstructs the image in front of or behind the retina (out of focus).", "topic": "Optics of vision: cornea as primary refractor, ciliary-muscle action, refraction concept", "citation": "Study Notes - Special Senses Physiology.txt L499-511: 'Refraction = change in direction ie. Bending... When light travels from a less dense medium into a more dense medium... In the eye, light travels from a less dense medium, the air, to a more dense medium, the eyeball... if the refraction is too much or too little, the arrow is reconstructed either in front of the retina or behind the retina... The cornea is primarily responsible for refraction and the lens will change shape to focus the image'; Sample SS questions Q2 answer C (cornea)", "corrected": false }, { "t": "Accommodation / ciliary muscle", "d": "Accommodation = focusing on near objects by ciliary-muscle contraction. For close objects corneal refraction is insufficient, so the ciliary muscle contracts and the lens becomes fatter/rounder (flat-oval to spherical), increasing refraction to focus on the retina. The lens is suspended from the ciliary muscle by zonular fibres.", "topic": "Optics of vision: cornea as primary refractor, ciliary-muscle action, refraction concept", "citation": "Study Notes - Special Senses Physiology.txt L516-533: 'Lens is connected to the ciliary muscle by zonular fibers... When images come very close... refraction provided by the cornea is insufficient... ciliary muscle contracts which causes the lens to get fatter... increases the amount of refraction... Contraction of the ciliary muscles causes the lens to go from a fairly flat, oval shape to fairly fat spherical shape... Accommodation -> the process of using the ciliary muscles in the lens in order to focus on objects that are very close'", "corrected": false }, { "t": "Myopia (nearsightedness)", "d": "Eyeball too LONG, so the image focuses in FRONT of the retina (too much refraction); can see near but not far. Corrected with CONCAVE (diverging) lenses to reduce refraction, or by laser surgery.", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L537-545: 'Myopia -> nearsightedness... Can focus on objects up close but not far away... The eyeball is too long and too much refraction occurs... reconstructed at a point in front of the retina... Corrected for by wearing glasses or contact lenses with a concave shape to them to reduce the amount of refraction... Corrected for by laser surgery'; Sample SS questions Q11 answer B (too long = myopia/concave)", "corrected": false }, { "t": "Hyperopia (farsightedness)", "d": "Eyeball too SHORT, so the image focuses BEHIND the retina (insufficient refraction); can see far but not near. Corrected with CONVEX (converging) lenses to increase refraction, or by laser surgery.", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L546-552: 'Hyperopia -> farsightedness... Can focus on objects far away but not up close... The eyeball is too short and the visual image is reconstructed behind the retina as there is not enough refraction... Corrected for either by glasses or contact lens with a convex lens to increase the amount of refraction... Corrected for by laser surgery for hyperopia'; Sample SS questions Q4 answer A (eyeball too short)", "corrected": false }, { "t": "Presbyopia", "d": "Age-related loss of the ability to accommodate for near vision (~age 45). Per the course, it is due to loss of lens elasticity from breakdown of the ciliary muscles, which can no longer reshape the lens.", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L535-536 + L531-533: 'Presbyopia -> loss of elasticity of the lens resulting in the inability to accommodate for near vision; due to the breakdown of the ciliary muscles; age-related'; '...lose the ability to accommodate at around 45 years of age due to the breakdown of the ciliary muscles'", "corrected": false }, { "t": "Astigmatism", "d": "A refractive defect caused by an oblong (irregularly curved) eyeball/cornea, distorting the focused image. Corrected with glasses or with more complex laser surgery.", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L553-554: 'Astigmatism -> oblong shape of the eyeball is the problem... Corrected for with glasses or with complex laser surgery'", "corrected": false }, { "t": "Glaucoma", "d": "Build-up of aqueous humour raises intraocular pressure; the pressure pushes on lens -> vitreous humour -> retina, damaging the photoreceptors. Per the course there is no successful treatment and the long-term visual prognosis is poor. (Clinically it is in fact manageable by lowering intraocular pressure.)", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L555-561: 'Glaucoma -> damage to the photoreceptors due to increased intraocular pressure... Buildup of aqueous humour which pushes back on the lens; the lens in turn pushes back on the vitreous humour which... pushes back on the retina and the photoreceptors, damaging them... No successful treatment... the prognosis is not good'; contrast Vander 16e ch7 L2955-2956", "corrected": false }, { "t": "Cataracts", "d": "Age-related clouding/greying of the lens as lens cells die and debris accumulates, impairing clear vision. Treated by removing the lens and inserting a synthetic (silicone) lens — which cannot accommodate.", "topic": "Defects/disorders of vision (myopia, hyperopia, presbyopia, astigmatism, glaucoma, cataracts)", "citation": "Study Notes - Special Senses Physiology.txt L562-567: 'Cataracts -> clouding of the lens... Age-related... Cells of the lens die and debris builds up within them causing a graying of the lens and the inability to see clearly... Treated by taking out the lens and putting in a silicone lens or a fake lens... A fake lens will not be able to accommodate'", "corrected": false }, { "t": "Visual fields → retina mapping", "d": "The LATERAL half of the field of view falls on the NASAL retina; the MEDIAL half of the field falls on the TEMPORAL retina (the lens inverts the image). Information from the nasal retina (lateral field) is what crosses at the optic chiasm.", "topic": "Visual pathways & fields (optic chiasm, nasal vs temporal retina crossing, lateral geniculate nucleus, visual cortex)", "citation": "Study Notes - Special Senses Physiology.txt L750-766: 'Information from the lateral half of the field of view hits the nasal region of the retina... information from the nasal retina crosses to the contralateral... side... at the optic chiasm... Information from the medial half of the field of view -> temporal region of the retina... does not cross at the optic chiasm -> stays on the same (ipsilateral) side'; Sample SS questions Q14 answer C (nasal; temporal; lateral)", "corrected": false }, { "t": "Visual pathway (chiasm → LGN → cortex)", "d": "Retinal ganglion cell axons → optic nerve → optic chiasm (nasal-retina fibres cross to the contralateral side; temporal-retina fibres stay ipsilateral) → lateral geniculate nucleus (LGN) of the thalamus → visual cortex in the occipital lobe. Each eye thus projects to both hemispheres.", "topic": "Visual pathways & fields (optic chiasm, nasal vs temporal retina crossing, lateral geniculate nucleus, visual cortex)", "citation": "Study Notes - Special Senses Physiology.txt L748 + L750-762: 'Visual cortex -> in the occipital lobe'; nasal retina 'crosses to the contralateral... side... at the optic chiasm -> synapses in the lateral geniculate nucleus -> neurons from the lateral geniculate nucleus take the information to the visual cortex'; temporal retina stays ipsilateral; 'Visual information from each eye goes both to the same side of the brain and also the contralateral side'", "corrected": false }, { "t": "Sound transmission path (air → fluid)", "d": "Sound funnels via pinna and external auditory canal → vibrates the tympanic membrane → ossicles malleus → incus → stapes (act as levers that AMPLIFY the vibration) → stapes pushes on the OVAL WINDOW → fluid (perilymph) movement in the cochlea. Amplification is needed because vibrations pass from air (outer/middle ear) into fluid (inner ear).", "topic": "Ear anatomy & sound transmission (outer/middle/inner ear, ossicles, oval/round window, cochlea compartments, perilymph/endolymph)", "citation": "Study Notes - Special Senses Physiology.txt L803-844: 'outer ear and the external auditory canal funnel... toward the middle and inner ear... hit the tympanic membrane... Tympanic membrane -> malleus -> incus -> stapes... Bones act as levers and amplify the sound... outer ear and the middle ear are both filled with air and the inner ear... is filled with fluid... The vibrations pass from air to fluid... Stapes... terminates on... the oval window... cochlea... is full of fluid'", "corrected": false }, { "t": "Three cochlear compartments and their fluids", "d": "Cochlea (inner ear) has three compartments: scala vestibuli (top, PERILYMPH), scala tympani (bottom, PERILYMPH), and the cochlear duct (middle, ENDOLYMPH). The cochlear duct houses the organ of Corti and its hair cells; endolymph's high K+ drives hair-cell depolarization.", "topic": "Ear anatomy & sound transmission (outer/middle/inner ear, ossicles, oval/round window, cochlea compartments, perilymph/endolymph)", "citation": "Study Notes - Special Senses Physiology.txt L849-856 + L865-877: 'Cochlea... Divided into 3 compartments: scala vestibuli (top), scala tympani (bottom) and cochlear duct (middle)... Scala vestibuli -> perilymph; Scala tympani -> perilymph; Cochlear duct -> endolymph; region of inner ear where the sensory receptors... are located'; hair cells on Organ of Corti in cochlear duct; stereocilia of inner hair cells 'extend into the endolymph'; Sample SS questions Q10 answer B (depolarizes due to inward K+)", "corrected": false } ], "ans": [ { "t": "Nicotinic receptor subtypes (NM vs NN)", "d": "Two cholinergic ionotropic (ligand-gated ion channel) receptor subtypes. NM (nicotinic muscle): on skeletal muscle at the NMJ, binds ACh from somatic motor neurons. NN (nicotinic nerve): on the cell bodies of postganglionic neurons at ALL autonomic ganglia (and the adrenal medulla), binds ACh from preganglionic endings.", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Study Notes - ANS 2023, Lec 2 rec 9 (L472-499): 'NM -> (nicotinic muscle) found in the somatic nervous system; found in skeletal muscle at the neuromuscular junction... NN -> (nicotinic nerve) found... on the cell bodies of the postganglionic neurons at all autonomic ganglia'; L499: 'Adrenal medulla also contains the NN type'; corroborated Vander 16e Ch6 L5775 ('postganglionic cells have predominantly nicotinic acetylcholine receptors') & L5787-5788 (skeletal muscle cholinergic receptors are nicotinic)", "corrected": false }, { "t": "Nicotinic (NN) transmission at autonomic ganglia", "d": "NN is ionotropic, so ganglionic transmission is ALWAYS excitatory: ACh opens the channel, Na+ moves in (and some K+ out) with a net Na+ influx, depolarising the postganglionic cell to produce an EPSP that triggers voltage-gated Na+ channels and an action potential.", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Study Notes - ANS 2023, Lec 2 rec 9 (L486-495: 'ACh binding to the NN receptor opens the channel, allowing sodium and potassium... larger movement of sodium... depolarization... and the production of an EPSP') & rec 10 (L552-559: 'EPSP will cause the opening of voltage-gated sodium channels... and generation of an action potential'); FAQs ANS #1 (L7-13): 'it always causes excitation, as the nicotinic nerve receptor is ionotropic'", "corrected": false }, { "t": "Muscarinic receptors (M1-M5)", "d": "Cholinergic metabotropic receptors with 5 subtypes (M1-M5), found on autonomic effector tissues (smooth/cardiac muscle, glands) plus sweat glands. Coupled to a G-protein signal-transduction mechanism, so ACh binding can EXCITE or INHIBIT the target depending on the G-protein/second-messenger pathway.", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Study Notes - ANS 2023, Lec 2 rec 9 (L501-508): 'Muscarinic receptors... 5 subtypes (M1 to M5)... Metabotrophic... coupled to a G-protein signal transduction mechanism... causes excitation or inhibition of the target tissue'; sweat-gland muscarinic per L528-529 & Sample Q15 key (M on sweat glands); Vander 16e Ch6 L5786 (effector ACh receptors are muscarinic) & L4276 (muscarinic are metabotropic, couple with G proteins)", "corrected": false }, { "t": "Adrenergic receptors (alpha vs beta)", "d": "Metabotropic receptors that bind noradrenaline/adrenaline; 2 types: alpha (2 subtypes) and beta (3 subtypes). G-protein-coupled, so binding can excite OR inhibit the target tissue depending on the receptor subtype and second-messenger pathway.", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Study Notes - ANS 2023, Lec 2 rec 9 (L510-517): 'Adrenergic receptors... Bind NE or E... 2 types: alpha (2 subtypes) and beta (3 subtypes)... Metabotrophic... coupled to a G-protein... causes excitation or inhibition'; Vander 16e Ch6 L4482-4483: 'alpha-adrenergic receptors... and beta-adrenergic receptors... All catecholamine receptors are metabotropic, and thus use second messengers'", "corrected": false }, { "t": "Ionotropic vs metabotropic receptors (ANS)", "d": "Ionotropic = receptor IS a ligand-gated ion channel; binding opens the pore directly (fast, always excitatory) — e.g. nicotinic NN/NM. Metabotropic = receptor coupled to a G-protein that alters an enzyme/ion channel via second messengers (slower, can excite or inhibit) — e.g. muscarinic and adrenergic receptors. This is why ganglionic (nicotinic) transmission is always excitatory but target-tissue responses vary.", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Study Notes - ANS 2023, Lec 2 rec 9 (L480-485: 'ionotropic receptor - a receptor which is also a ligand-gated ion channel') & rec 10 (L538: ionotropic = 'opening an ion channel'; L561-572: metabotropic, 7 transmembrane domains, G-protein pathway); FAQs ANS #1 (L7-21): NN ionotropic 'always causes excitation', muscarinic/adrenergic metabotropic 'can be stimulatory... or inhibitory'", "corrected": false }, { "t": "Metabotropic signal-transduction cascade order", "d": "Transmitter (ACh/NE) binds the metabotropic receptor → activates a G-protein → G-protein activates a membrane-bound enzyme → enzyme generates a second messenger → second messenger activates a protein kinase, altering channel/enzyme activity and the cellular response (order: G, E, S, P).", "topic": "Receptor types, subtypes, and signaling mechanism (nicotinic NM vs NN; muscarinic M1-M5; adrenergic alpha vs beta; ionotropic vs metabotropic / G-protein)", "citation": "Sample ANS questions Q14 (L130-140, answer key L188 = 'e. G, E, S, P'); mechanism in Study Notes Lec 2 rec 10 (L567-572): transmitter binds receptor -> 'activate proteins called G proteins... G proteins affect the activity of an enzyme... induce a series of steps... produce a response'", "corrected": false }, { "t": "Sympathetic chain (paravertebral) ganglia", "d": "The sympathetic trunk: a chain of ganglia running parallel to the spinal cord on each side. The first (most common) destination for a sympathetic preganglionic fibre, which has a SHORT preganglionic and LONG postganglionic axon. Autonomic axons leave the cord via the ventral roots.", "topic": "Sympathetic ganglia organization and pathways (chain/paravertebral vs collateral/prevertebral ganglia, splanchnic nerves, the 3 preganglionic pathways, white vs grey rami communicantes)", "citation": "Study Notes - ANS 2023, Lec 1 rec 3 (L186-201): 'Sympathetic chain/trunk (paravertebral ganglia - run parallel to spinal cord)... Axons of the autonomic neurons leave the spinal cord via the ventral roots'; SNS short pre / long post axon per Lec 1 rec 3 (L156-157); Vander 16e Ch6 L5720-5723 ('chains of ganglia—one on each side of the cord—known as the sympathetic trunks')", "corrected": false }, { "t": "Collateral (prevertebral) ganglia", "d": "The second set of sympathetic ganglia, lying in front of the vertebral column near the abdominal viscera: the celiac, superior mesenteric, and inferior mesenteric ganglia. A preganglionic fibre passes through the sympathetic trunk without synapsing (as a splanchnic nerve) and synapses here; they innervate abdominal and pelvic viscera.", "topic": "Sympathetic ganglia organization and pathways (chain/paravertebral vs collateral/prevertebral ganglia, splanchnic nerves, the 3 preganglionic pathways, white vs grey rami communicantes)", "citation": "Study Notes - ANS 2023, Lec 1 rec 3 (L203-214): 'Collateral ganglia... Second set of ganglia... Also called pre-vertebral ganglia... celiac ganglion, the superior mesenteric ganglion, and the inferior mesenteric ganglion... Innervate abdominal and pelvic viscera'; splanchnic-nerve passthrough per Lec 1 rec 4 (L225-226); FAQs ANS #4 (L102-108); Vander 16e Ch6 L5724-5726", "corrected": false }, { "t": "Three pathways of a sympathetic preganglionic fibre", "d": "On leaving the cord via the ventral root, a sympathetic preganglionic fibre can: (1) synapse immediately with a postganglionic neuron in the chain ganglion at the same level; (2) travel up or down the chain and synapse at another level; or (3) pass through the chain without synapsing and continue as a splanchnic nerve to a collateral ganglion.", "topic": "Sympathetic ganglia organization and pathways (chain/paravertebral vs collateral/prevertebral ganglia, splanchnic nerves, the 3 preganglionic pathways, white vs grey rami communicantes)", "citation": "Study Notes - ANS 2023, Lec 1 rec 4 (L220-226): '3 pathways a sympathetic preganglionic fiber can take... 1. Synapse immediately... at same level 2. Travel up or down the chain and synapse in ganglia at other levels 3. Pass through chain without synapsing, continue to collateral ganglion as splanchnic nerve'; ventral-root exit per L220", "corrected": false }, { "t": "White vs grey rami communicantes", "d": "Branches connecting a spinal nerve to the sympathetic chain ganglion. White ramus = carries the MYELINATED preganglionic fibre INTO the ganglion (myelin makes it white). Grey ramus = carries the UNMYELINATED postganglionic fibre back OUT to the spinal nerve.", "topic": "Sympathetic ganglia organization and pathways (chain/paravertebral vs collateral/prevertebral ganglia, splanchnic nerves, the 3 preganglionic pathways, white vs grey rami communicantes)", "citation": "Study Notes - ANS 2023, Lec 1 rec 4 (L227-235): 'White ramus communicans -> the branch that leads into the ganglion from the spinal nerve... carrying a myelinated preganglionic fiber; it is the myelin that makes it appear white. Grey ramus communicans -> the branch that goes back into the spinal nerve... carrying an unmyelinated postganglionic fiber' (course-specific; terms not used in Vander Ch6)", "corrected": false }, { "t": "Dorsal vs ventral root (autonomic outflow)", "d": "Dorsal root = sensory inflow (afferent axons carrying sensory info INTO the cord). Ventral root = motor outflow; autonomic (and somatic) efferent axons LEAVE the cord via the ventral root to carry motor commands to target tissue.", "topic": "Sympathetic ganglia organization and pathways (chain/paravertebral vs collateral/prevertebral ganglia, splanchnic nerves, the 3 preganglionic pathways, white vs grey rami communicantes)", "citation": "Study Notes - ANS 2023, Lec 1 rec 3 (L191-201): 'Dorsal root - pathway into spinal cord; carries sensory information... contains axons of afferent/sensory neurons. Ventral root - pathway leaving spinal cord; carries motor information away... Axons of the autonomic neurons leave the spinal cord via the ventral roots'", "corrected": false }, { "t": "Autonomic tone", "d": "A background level of activity maintained by BOTH sympathetic and parasympathetic divisions — neither is ever fully off. Allows fine bidirectional control: a target can be turned up or down from its resting baseline rather than just switched on.", "topic": "Dual autonomic innervation: autonomic tone, reciprocal activation, and antagonistic vs cooperative effects", "citation": "Study Notes - ANS 2023, Lec 2 rec 7 (L315-321): 'Tone -> a background level of activity maintained by both sympathetic and parasympathetic divisions... never completely off; there is always a low level of activity in either division... gives more control over body responses'", "corrected": false }, { "t": "Reciprocal activation (dual innervation)", "d": "In organs with dual (sympathetic + parasympathetic) innervation, the two divisions are activated reciprocally: as one increases its activity the other decreases. Fight-or-flight raises sympathetic and lowers parasympathetic tone; rest-and-digest does the reverse — giving precise control over the response.", "topic": "Dual autonomic innervation: autonomic tone, reciprocal activation, and antagonistic vs cooperative effects", "citation": "Study Notes - ANS 2023, Lec 2 rec 7 (L310-332): 'Most target organs and tissues receive dual autonomic innervation... Activated reciprocally -> activity of one system will increase and the activity of the other system will decrease... Fight or flight response: activity of the sympathetic system increases and activity of the parasympathetic system decreases... Rest or digest response: [the reverse]'", "corrected": false }, { "t": "Antagonistic vs cooperative dual innervation", "d": "Antagonistic (opposite) effects: e.g. heart — SNS speeds rate, PSNS slows it; GI tract — SNS decreases motility/secretion, PSNS increases them. Cooperative (working together) effects: e.g. salivary glands — both stimulate saliva (SNS = small volume of thick saliva, PSNS = large volume of watery saliva); male reproduction — PSNS drives erection, SNS drives emission.", "topic": "Dual autonomic innervation: autonomic tone, reciprocal activation, and antagonistic vs cooperative effects", "citation": "Study Notes - ANS 2023, Lec 2 rec 7 (L340-354): 'Antagonistic = opposite... GI tract: SNS decreases the activity... PSNS increases the activity... Heart: SNS acts to increase heart rate and the PSNS acts to decrease heart rate... Cooperative... salivary glands: both divisions stimulate saliva production... SNS... small amount of a thicker saliva; PSNS... large amount of a watery saliva... PSNS is responsible for erection... sympathetic division is responsible for emission'; Sample Q5 (pacemaker = antagonistic, key a)", "corrected": false }, { "t": "Exceptions to dual innervation", "d": "Three structures receive SYMPATHETIC innervation only (no parasympathetic): the adrenal medulla, most blood vessels, and sweat glands. (Parasympathetic vasodilation is a noted exception only in the penis/clitoris.)", "topic": "Dual autonomic innervation: autonomic tone, reciprocal activation, and antagonistic vs cooperative effects", "citation": "Study Notes - ANS 2023, Lec 2 rec 7 (L336-339): 'Adrenal medulla, most blood vessels in the body and the sweat glands receive sympathetic innervation only'; penis/clitoris PSNS-vasodilation exception per Lec 2 rec 6 (L304-306); Sample Q6 (adrenal medulla, key b)", "corrected": false }, { "t": "Both divisions can be excitatory or inhibitory", "d": "It is INCORRECT to say sympathetic is always excitatory and parasympathetic always inhibitory. The effect on a given target depends on the target tissue, the neurotransmitter released, and the receptor subtype (and its metabotropic mechanism) to which it binds.", "topic": "Dual autonomic innervation: autonomic tone, reciprocal activation, and antagonistic vs cooperative effects", "citation": "Study Notes - ANS 2023, Lec 2 rec 7 (L355-359): 'It is not correct to say that the sympathetic system is always excitatory and the parasympathetic system always inhibitory... Activity depends on the target tissue, neurotransmitter released and the receptor to which neurotransmitter binds'; FAQs ANS #1 (L3-5)", "corrected": false }, { "t": "Varicosity", "d": "A chain of swellings along the axon branches of an autonomic POSTganglionic neuron (both SNS and PSNS) where neurotransmitter is synthesised and stored in vesicles. Unlike a single synaptic knob, varicosities release transmitter along a long stretch of axon over a large surface of the effector, affecting many target cells at once.", "topic": "Neurotransmitter synthesis/termination and varicosities (ACh synthesis & acetylcholinesterase breakdown; NE synthesis tyrosine->dopa->dopamine->NE and reuptake; varicosity structure/function)", "citation": "Study Notes - ANS 2023, Lec 2 rec 8 (L420-431): 'Postganglionic fibers... do not terminate in a single swelling like the synaptic knob... Varicosity -> swellings along the axon branches of a postganglionic neuron; site where the neurotransmitters are made and stored in vesicles; release neurotransmitters along a significant length of the axon... over a large surface area... Found on both sympathetic and parasympathetic postganglionic neurons'; FAQs ANS #3 (L55-71)", "corrected": false }, { "t": "ACh synthesis and breakdown (cholinergic terminal)", "d": "ACh is synthesised from acetyl-CoA + choline by choline acetyltransferase and packaged into vesicles. After Ca2+-triggered exocytosis and receptor binding, acetylcholinesterase in the cleft breaks ACh into choline + acetate; choline is recycled into the terminal to make new ACh, terminating the signal.", "topic": "Neurotransmitter synthesis/termination and varicosities (ACh synthesis & acetylcholinesterase breakdown; NE synthesis tyrosine->dopa->dopamine->NE and reuptake; varicosity structure/function)", "citation": "Study Notes - ANS 2023, Lec 2 rec 8 (L394-418): 'ACh -> synthesized from acetyl-CoA and choline in the nerve terminal... catalyzed by an enzyme called choline acetyltransferase... packaged into vesicles... released by exocytosis... acetylcholinesterase, breaks down ACh to choline and acetate... Choline is recycled back into the nerve terminal... to make more ACh'", "corrected": false }, { "t": "NE synthesis and termination (adrenergic varicosity)", "d": "Noradrenaline is synthesised from tyrosine -> dopa -> dopamine, then converted to NE inside vesicles. Released by Ca2+-triggered exocytosis onto adrenergic receptors. Its action is terminated PRIMARILY by REUPTAKE of the intact NE molecule back into the varicosity (not enzymatic breakdown), where it is repackaged for reuse.", "topic": "Neurotransmitter synthesis/termination and varicosities (ACh synthesis & acetylcholinesterase breakdown; NE synthesis tyrosine->dopa->dopamine->NE and reuptake; varicosity structure/function)", "citation": "Study Notes - ANS 2023, Lec 2 rec 8 (L436-455): 'Synthesized from the amino acid tyrosine... converted to dopa and dopamine... Dopamine is taken up into vesicles where it is converted to NE... terminated by the uptake of NE into the varicosity; the whole molecule is taken up and not broken down... repackaged into vesicles... the primary mechanism for terminating NE action is reuptake into the nerve terminal'; Vander 16e Ch6 L4326-4335 (tyrosine->L-dopa; decline 'mainly because a... transporter... transports the catecholamine back into the axon terminal')", "corrected": false }, { "t": "Convergence vs divergence (ANS)", "d": "Convergence = many preganglionic neurons synapse onto a single postganglionic neuron (information converges). Divergence = a few preganglionic neurons synapse onto many postganglionic neurons (information spreads out). Both exist in the nervous system; the ANS shows divergence at the ganglia.", "topic": "Convergence and divergence at the ganglia (mass discharge; SNS 1-20 vs PSNS 1-3 pre:post ratios)", "citation": "Study Notes - ANS 2023, Lec 2 rec 11 (L576-585): 'Convergence -> numerous preganglionic neurons form synapses with a single postsynaptic neuron... Divergence -> a small number of presynaptic neurons form synapses with a larger number of postsynaptic neurons... In the ANS divergence exists at the ganglia'", "corrected": false }, { "t": "Divergence ratios and mass discharge (SNS vs PSNS)", "d": "The SNS diverges far more than the PSNS. Sympathetic pre:post ratio ~1:20 -> diffuse 'mass discharge' affecting many organs at once during fight-or-flight. Parasympathetic ratio ~1:3 -> more specific, localised responses.", "topic": "Convergence and divergence at the ganglia (mass discharge; SNS 1-20 vs PSNS 1-3 pre:post ratios)", "citation": "Study Notes - ANS 2023, Lec 2 rec 11 (L586-598): 'SNS exhibits a greater degree of divergence than the PSNS... PSNS: the ratio of preganglionic neuron synapsing with postganglionic neuron is between 1 and 3; more specific/localized responses... SNS: the ratio... can be anywhere between 1 and 20... mass discharge occurs where many organs and tissues... are affected'", "corrected": false }, { "t": "Integrating centres for autonomic reflexes", "d": "Autonomic reflexes are integrated at several CNS levels: SPINAL CORD (e.g. sacral reflexes for urination, defecation, erection); MEDULLA OBLONGATA (blood pressure regulation, salivation, swallowing, vomiting, respiration); and the HYPOTHALAMUS — the 'head ganglion' of the ANS — which regulates temperature and modulates lower centres.", "topic": "Integrating centers for autonomic reflexes (spinal cord, medulla oblongata, hypothalamus as the 'head ganglion')", "citation": "Study Notes - ANS 2023, Lec 2 rec 11 (L600-611): 'Spinal cord... sacral region can act as integrative centers for autonomic reflexes, such as urination, defecation, and erection... Medulla oblongata plays a role in reflexes, such as blood pressure regulation, salivation, swallowing, vomiting, and respiration... Hypothalamus... The head ganglion of the autonomic nervous system... Regulates temperature'", "corrected": false }, { "t": "Somatic vs autonomic efferent architecture", "d": "Somatic: a SINGLE neuron from CNS to skeletal muscle with one synapse (NMJ); axon large and myelinated; always uses ACh; voluntary. Autonomic: a TWO-neuron chain in series (preganglionic + postganglionic) linked by a synapse in a ganglion outside the CNS; involuntary; uses ACh, NE, or E.", "topic": "Explicit somatic-vs-autonomic structural comparison (single somatic neuron + NMJ vs the two-neuron preganglionic/postganglionic autonomic chain)", "citation": "Study Notes - ANS 2023, Lec 1 rec 2 (L89-137): 'SNS: Single neuron from CNS to skeletal muscle... Single synapse at the skeletal muscle... Axons... large and myelinated... Neurotransmitter always ACh; Control is voluntary. ANS: Organized into a chain of two neurons in series... preganglionic and postganglionic neurons... Control is Involuntary... Neurotransmitter can be: ACh, NE, E'; Sample Q1, Q3", "corrected": false } ], "blood": [ { "t": "Active vs passive immunity", "d": "Active: host's own immune system makes the antibodies after exposure to antigen (natural infection or vaccination) — slow to develop (days–weeks) but long-lasting (months–years) and confers memory. Passive: pre-formed antibodies are transferred from another source — immediate but short-lived, with no memory.", "topic": "Active vs passive immunity and immunization / vaccination", "citation": "Study Notes- Blood Physiology.txt L559-571 ('Two types of immunity... active immunity: ...antibodies are self-generated... not immediate- days to weeks... Duration: months to years. Passive immunity: pre-formed antibodies are transferred... immediate... short-lived'); corroborated Vander 16e ch18 L2383-2406 ('active immunity'; passive immunity 'short-lived, usually lasting only a few weeks or months')", "corrected": false }, { "t": "Active immunity", "d": "Immunity from the host's own antibody production following direct exposure to an antigen (natural infection) or exposure by vaccination. Self-generated antibodies; not immediate (takes days to weeks) but lasts months to years and protects against future infection (basis of vaccines).", "topic": "Active vs passive immunity and immunization / vaccination", "citation": "Study Notes- Blood Physiology.txt L560-565 ('Active immunity: Direct exposure to the antigen or exposure by vaccination... antibodies are self-generated... not immediate- days to weeks... Duration: months to years... Combat future infection'); Vander 16e ch18 L2383-2394", "corrected": false }, { "t": "Passive immunity", "d": "Immunity from pre-formed antibodies transferred from another individual — e.g. mother to fetus across the placenta during pregnancy or to the infant via nursing (breast milk). Acquired immediately but short-lived; provides protection until the child's own immune system matures. No immunological memory is generated.", "topic": "Active vs passive immunity and immunization / vaccination", "citation": "Study Notes- Blood Physiology.txt L566-571 ('Passive immunity: ...pre-formed antibodies are transferred from a mother to the fetus during pregnancy or by nursing... immediate... short-lived... until their own immune system is fully developed'); Vander 16e ch18 L2395-2406 (placental IgG, breast-milk IgA; 'relatively short-lived')", "corrected": false }, { "t": "Vaccination & immunological memory", "d": "A primary immune response is slow and produces little antibody; the body remembers the antigen so a re-exposure triggers a fast, large secondary response. Vaccination exploits this memory — controlled antigen exposure generates active immunity and memory cells without disease, protecting against later infection.", "topic": "Active vs passive immunity and immunization / vaccination", "citation": "Study Notes- Blood Physiology.txt L546-557 ('primary immune response -> slow to develop and the amount of antibody generated is not large... if exposed to the same antigen again, the host responds in a fast and quick manner... secondary response... This feature of memory is effectively used for vaccination'); Vander 16e ch18 L2384-2394", "corrected": false }, { "t": "Five WBC types & functions", "d": "Granulocytes — Neutrophils (phagocytes), Eosinophils (defence against parasites), Basophils (inflammation); plus Monocytes (phagocytes that leave blood and become tissue macrophages) and Lymphocytes (B cells = antibody/humoral immunity, T cells = cellular immunity). Granulocytes are classified by cytoplasmic granule staining and nuclear lobe shape.", "topic": "WBC differential — eosinophils and basophils (full leukocyte types and their distinct functions)", "citation": "Study Notes- Blood Physiology.txt L62-87 ('granulocyte white blood cells are classified according to staining characteristics of cytoplasmic granules and structure of the nuclear lobes... Neutrophils: phagocytes; Eosinophils: defense against parasites; Basophils: inflammation; Monocytes: phagocytes... transformed into tissue macrophages; Lymphocytes: B-cell antibody/humoral, T-cell cellular'); grouping matches Blood Lecture 1 pdf L154-157", "corrected": false }, { "t": "Eosinophils & basophils", "d": "Both are granulocytes. Eosinophils: defence against parasites (also active in allergic reactions). Basophils: mediate inflammation (release histamine and other inflammatory mediators). Distinguished from neutrophils by the staining of their cytoplasmic granules.", "topic": "WBC differential — eosinophils and basophils (full leukocyte types and their distinct functions)", "citation": "Study Notes- Blood Physiology.txt L69-73 ('Eosinophils: defense against parasites; Basophils: inflammation'); the added detail corroborated by Vander 16e ch18 L228-229 (eosinophils 'Destroy multicellular parasites; Participate in immediate hypersensitivity reactions') & L338 (basophils 'Release histamine and other chemicals involved in inflammation')", "corrected": false }, { "t": "Clotting factor deficiencies", "d": "Bleeding severity depends on which factor is missing: Factor VII deficiency → serious bleeding; Factor VIII deficiency → severe bleeding (haemophilia); Factor XI deficiency → moderate bleeding; Factor XII deficiency → no bleeding in vivo (clotting is initiated via Factor VII), but blood fails to clot in a glass test tube in vitro.", "topic": "Clotting-factor deficiencies and hemophilia", "citation": "Study Notes- Blood Physiology.txt L885-893 ('A deficiency in factor VII causes serious bleeding... factor VIII... severe bleeding... factor XI causes moderate bleeding... factor XII causes no bleeding problem in vivo, but blood does not clot in the glass test tube in vitro... Clotting is not initiated by factor XII, but rather via activation of factor VII'); Blood Lecture 6 pdf L166-175", "corrected": false }, { "t": "Haemophilia", "d": "Bleeding disorder caused by a lack of Factor VIII, producing severe bleeding; affected individuals are called haemophiliacs. The intrinsic-pathway clotting factor deficiency impairs amplification of thrombin (and thus fibrin) formation.", "topic": "Clotting-factor deficiencies and hemophilia", "citation": "Study Notes- Blood Physiology.txt L887-888 ('Individuals that lack factor VIII experience severe bleeding and are known as hemophiliacs'); mechanism corroborated by Vander 16e ch12 L9073-9077 (factor VIIIa is a cofactor in the intrinsic pathway) & L9110-9115 (intrinsic pathway 'generates the large amounts of thrombin required for adequate coagulation')", "corrected": false }, { "t": "Platelet production (megakaryocytes & thrombopoietin)", "d": "Platelets (thrombocytes) arise from pluripotent bone-marrow stem cells that differentiate into large cells called megakaryocytes; platelets are pinched off from megakaryocyte cytoplasm. Thrombopoietin is the cytokine/growth factor that regulates platelet production (cf. erythropoietin for RBCs).", "topic": "Platelet production: megakaryocytes and thrombopoietin", "citation": "Study Notes- Blood Physiology.txt L601-605 ('Platelets originate from the pluripotent stem cells of the bone marrow... converted to cells called megakaryocytes... Platelets are pinched off from the cytoplasmic part of megakaryocytes') & L102-103 ('Thrombopoietin – regulates production of platelets'; 'Erythropoietin – regulates production of RBCs'); Blood Lecture 5 pdf L74-93", "corrected": false }, { "t": "Causes of anaemia (classification)", "d": "Anaemia = decreased oxygen-carrying capacity of blood from too few RBCs and/or too little haemoglobin. Causes: iron deficiency; pernicious (lack of intrinsic factor/B12); aplastic (bone-marrow damage from radiation/drugs); chronic kidney disease (low EPO); haemolytic (increased RBC breakdown); haemorrhagic (blood loss); and abnormal Hb structure (e.g. sickle cell).", "topic": "Anemia classification breadth (aplastic, hemorrhagic, hemolytic, chronic-kidney-disease anemia)", "citation": "Study Notes- Blood Physiology.txt L189-201 ('Anemia: decreased oxygen-carrying capacity of the blood due to a deficiency of RBCs and/or hemoglobin... Lack of iron; Pernicious anemia: lack of intrinsic factor or Vitamin B12; Aplastic anemia: damage of bone marrow due to radiation/drugs; Chronic kidney disease (reduced level of erythropoietin); Hemolytic... Hemorrhagic... Abnormal structure of hemoglobin') & L204-209 (sickle cell -> hemolytic)", "corrected": false }, { "t": "Aplastic, haemorrhagic & haemolytic anaemia", "d": "Aplastic anaemia: bone-marrow damage (radiation/drugs) reduces production of all blood cells. Haemorrhagic anaemia: increased blood loss (injury, bleeding ulcers, chronic menstruation). Haemolytic anaemia: increased RBC breakdown from abnormal RBC shape or immune reactions (e.g. mismatched transfusion).", "topic": "Anemia classification breadth (aplastic, hemorrhagic, hemolytic, chronic-kidney-disease anemia)", "citation": "Study Notes- Blood Physiology.txt L195-199 ('Aplastic anemia: damage of bone marrow due to radiation/drugs... Hemolytic anemia: increased breakdown due to abnormal shape of RBC or due to immune reactions during transfusion; Hemorrhagic anemia: increased blood loss due to injury, bleeding ulcers or chronic menstruation')", "corrected": false } ], "nms": [ { "t": "Stretch reflex (patellar/knee-jerk)", "d": "The simplest stimulus–response paradigm the nervous system can generate: tapping the patellar tendon stretches the quadriceps → stretch receptors fire the afferent neuron → it enters the spinal cord and synapses directly on the efferent (motor) neuron → quadriceps contracts → leg jerks. Muscle contraction in response to stretch.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L11-19 ('The stretch reflex is the simplest stimulus- response paradigm that the human nervous system can generate'; 'Patellar-tendon stretch reflex: tap the patellar tendon... quadriceps muscle stretches... causing it to contract → a jerk or swing of the foot outwards') and L13 ('Stretch reflex → muscle contraction in response to stretching within muscle')", "corrected": false }, { "t": "Reflex arc / reflex loop (components)", "d": "Circular pathway: receptor → afferent (sensory) neuron in via the DORSAL root → CNS (spinal cord) integration → efferent (motor) neuron out via the VENTRAL root → effector (muscle). Afferent in dorsally, efferent out ventrally.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L76-89 ('Afferent neurons → carry information from the periphery to the spinal cord via the dorsal roots'; 'Efferent neurons → carry information from the spinal cord to the periphery via the ventral roots'; 'Reflex loop: Circular in nature. Activation of a receptor will activate an afferent fiber which enters through the dorsal root... activate an efferent fiber which leaves through the ventral root... activate a muscle')", "corrected": false }, { "t": "Monosynaptic pathway of the stretch reflex", "d": "The afferent neuron makes DIRECT (monosynaptic) excitatory contact onto the efferent neuron supplying the quadriceps — only one synapse between sensory input and motor output — making it fast. The stretch reflex is the classic monosynaptic reflex.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L164-167 ('Afferent neuron makes direct monosynaptic contact onto the efferent neuron which innervates the quadriceps muscle... The excitatory efferent neuron which travels to the quadriceps muscle is activated, resulting in contraction of the quadriceps')", "corrected": false }, { "t": "Reciprocal inhibition (antagonist relaxation)", "d": "In the stretch reflex the afferent neuron also synapses onto an INHIBITORY interneuron, which inhibits the efferent neuron supplying the antagonist (hamstrings). The agonist (quadriceps) contracts while the antagonist is inhibited from contracting, so it does not oppose the movement.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L113-117 ('Interneuron in the stretch reflex is inhibitory. The afferent nerve fiber also synapses with an inhibitory interneuron. When activated, the inhibitory interneuron inhibits efferent neurons which innervate the hamstrings muscle. This inhibits contraction of the hamstrings muscle so that it does not interfere with the reflex response') and L169-175", "corrected": false }, { "t": "Afferent neuron of the stretch reflex (structure)", "d": "A pseudo-unipolar sensory neuron with its cell body in the DORSAL ROOT GANGLION. Its peripheral axon runs to the quadriceps to sense stretch; its central axon enters the CNS and makes two contacts — directly onto the quadriceps motor neuron and onto an inhibitory interneuron.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L144-149 ('Afferent neuron of stretch reflex: Sensory neuron... Pseudo-unipolar cell; Cell body located in dorsal root ganglion; Peripheral axon – extends from the cell body to the muscle; Central axon – from cell body into CNS and makes contact with other neurons') and L156-163 (two contacts: efferent to quadriceps + inhibitory interneuron). Corroborated by Sample NMS Q10, answer 'A' = dorsal root ganglion (L87-93, L192)", "corrected": false }, { "t": "Sensory transduction in the stretch reflex", "d": "Muscle stretch enlarges the sensory receptor on the afferent ending, opening stretch-gated Na⁺ channels → Na⁺ enters → graded depolarisation. If it reaches threshold (≈ −50 mV, ~10–15 mV above rest) voltage-gated Na⁺ channels open and an action potential fires in the afferent neuron.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L361-375 ('Muscle stretch... results in increased opening of specialized Na+ receptors, entry of Na+ into afferent fiber and depolarization... Muscle stretch = enlargement of sensory receptor and movement of Na+ ions through pores... Threshold is typically 10 to 15 mV more depolarized than resting membrane potential (we will use -50mV as threshold)... the result is the opening of voltage-gated Na+ channels and an action potential')", "corrected": false }, { "t": "Interneuron (role in reflexes)", "d": "A neuron located entirely within the CNS that carries information between neurons and can be either excitatory OR inhibitory (unlike afferents/efferents, which only excite). In the stretch reflex the interneuron is inhibitory, mediating reciprocal inhibition of the antagonist.", "topic": "The stretch reflex / reflex arc (and reciprocal inhibition of the antagonist)", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L44 ('Interneurons → carry information between neurons'), L45 ('Afferent neurons and efferent neurons: only activate/excite'), L51-52 ('Interneurons can either excite or inhibit other neurons; Located entirely within the CNS'), L109-117 (interneuron in stretch reflex is inhibitory)", "corrected": false }, { "t": "Indirectly-gated (metabotropic) synaptic transmission", "d": "Neurotransmitter binds a receptor that is a SEPARATE protein from the ion channel (receptor ≠ effector). It activates a G-protein → GTP activates adenylyl cyclase → ATP→cAMP (2nd messenger) → cAMP-activated protein kinase phosphorylates channels to open/close them. Slow onset, long-lasting.", "topic": "Indirectly-gated (metabotropic / second-messenger) synaptic transmission", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L639-646 ('Receptor and the effecter are not the same protein... binds to receptor and activates 2nd messenger system... via G-proteins; GTP activates adenylyl cyclase which converts ATP into cAMP, the 2nd messenger; cAMP activates protein kinases which phosphorylate a channel and cause it to open or close... Slow onset and long lasting'). Corroborated by Vander 16e Ch6 L3421-3422 (metabotropic receptors 'indirectly influence ion channels through a G protein and/or a second messenger') and Study & Review 6.10 L3610-3612", "corrected": false }, { "t": "Directly- vs indirectly-gated transmission (contrast)", "d": "Directly-gated (ionotropic): receptor IS the ion channel; fast onset, brief (msec); e.g. NMJ, EPSP/IPSP. Indirectly-gated (metabotropic): receptor coupled via G-protein/cAMP to a separate channel; slow onset, long-lasting. Vander terms these ionotropic vs metabotropic receptors.", "topic": "Indirectly-gated (metabotropic / second-messenger) synaptic transmission", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L601 ('2 types of chemical synaptic transmission: directly gated and indirectly gated'), L635-637 (directly-gated 'fast in onset and short lasting (msec)... Receptor is located directly on the ion channel'), L646 (indirectly-gated 'Slow onset and long lasting'). Vander 16e Ch6 L3419-3422 ('receptors themselves may be ion channels, which designates them as ionotropic... the receptors may indirectly influence ion channels through a G protein... metabotropic') and L3931-3932 (metabotropic 'slower in onset and longer in duration')", "corrected": false }, { "t": "Synaptic plasticity", "d": "Long-term changes in neurons produced by indirectly-gated (metabotropic) chemical transmission — the slow, lasting second-messenger effects allow synaptic strength to be modified over time, a basis for learning. Chemical synapses (not electrical) provide this flexibility.", "topic": "Indirectly-gated (metabotropic / second-messenger) synaptic transmission", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L660-661 ('Plasticity - refers to the process of indirectly-gated chemical synaptic transmission where long term changes in neurons are seen'); flexibility of chemical vs electrical synapses L648-659. Corroborated by Vander 16e Ch6 (long-term potentiation via metabotropic/second-messenger signaling, L4549-4574; plasticity, L3967)", "corrected": false }, { "t": "Withdrawal (flexor) reflex", "d": "A second reflex example introduced in the course: a painful/noxious stimulus drives a polysynaptic reflex that withdraws the limb from the stimulus. Unlike the monosynaptic stretch reflex, it involves interneurons (and reciprocal inhibition of antagonists to permit flexion).", "topic": "Withdrawal reflex", "citation": "Course: Study Notes- Nerve Muscle Synapse.txt L21-22 ('The Withdrawal Reflex: (This is another reflex we will look at)'). The polysynaptic/interneuron and reciprocal-inhibition characterization is corroborated by standard references (Costanzo Physiology; OpenStax Anatomy & Physiology — flexor/withdrawal reflex is a polysynaptic protective reflex with crossed-extensor reciprocal innervation).", "corrected": true } ], "gi": [ { "t": "Carbohydrate digestion (amylase)", "d": "Starch digestion begins in the mouth via salivary amylase but is inactivated by gastric acid; ~95% is completed in the small intestine by pancreatic amylase. The products are the disaccharide maltose plus short, branched glucose chains.", "topic": "Carbohydrate digestion and absorption", "citation": "Vander's 16e Ch 15 §15.6 'Carbohydrate' (p.557): 'The digestion of starch by salivary amylase begins in the mouth... It continues very briefly in the upper part of the stomach before gastric acid inactivates the amylase. Most (~95% or more) starch digestion is completed in the small intestine by pancreatic amylase.' p.558: 'The products of both salivary and pancreatic amylase are the disaccharide maltose and a mixture of short, branched chains of glucose molecules.'", "corrected": false }, { "t": "Brush-border carbohydrate enzymes", "d": "Maltose and ingested disaccharides (sucrose, lactose) are split into monosaccharides — glucose, galactose, and fructose — by enzymes on the apical (brush-border) membrane of intestinal epithelial cells before absorption. Only monosaccharides can be absorbed.", "topic": "Carbohydrate digestion and absorption", "citation": "Vander's 16e Ch 15 §15.6 'Carbohydrate' (p.558): 'These products, along with ingested sucrose and lactose, are broken down into monosaccharides—glucose, galactose, and fructose—by enzymes located on the apical membranes of the small-intestine epithelial cells (brush border).' Contrast with protein (p.558): peptide absorption 'contrasts with carbohydrate absorption, in which molecules larger than monosaccharides are not absorbed.'", "corrected": false }, { "t": "Monosaccharide absorption: SGLT vs GLUT", "d": "Glucose and galactose are absorbed across the apical membrane by secondary active transport coupled to Na⁺ via SGLT (sodium–glucose cotransporter); fructose enters by facilitated diffusion via GLUT. All three exit the cell across the basolateral membrane via GLUT transporters, powered ultimately by the basolateral Na⁺/K⁺-ATPase.", "topic": "Carbohydrate digestion and absorption", "citation": "Vander's 16e Ch 15 §15.6 (p.558, Fig 15.29): 'Fructose enters the epithelial cells by facilitated diffusion via... glucose transporters (GLUTs), whereas glucose and galactose undergo secondary active transport coupled to Na+ via a sodium–glucose cotransporter (SGLT). These monosaccharides then leave the epithelial cells... by way of facilitated diffusion via various GLUT proteins in the basolateral membranes... The energy required for absorption is provided primarily by Na+/K+-ATPase pumps on the basolateral membrane.'", "corrected": false }, { "t": "Protein digestion pathway", "d": "Proteins are partially broken to peptide fragments in the stomach by pepsin (active only at low pH), then digested in the small intestine by pancreatic trypsin, chymotrypsin, and carboxypeptidases, and finally by brush-border aminopeptidases/carboxypeptidases that split off terminal amino acids. End products are amino acids and small (di-/tri-) peptides.", "topic": "Protein digestion and absorption", "citation": "Vander's 16e Ch 15 §15.6 'Protein' (p.558): 'Proteins are first partially broken down to peptide fragments in the stomach by the enzyme pepsin. Further breakdown is completed in the small intestine by the enzymes trypsin and chymotrypsin... These peptide fragments... are further digested to free amino acids by carboxypeptidases (additional proteases secreted by the pancreas) and aminopeptidases, located on the apical membranes of the small-intestine epithelial cells.'", "corrected": false }, { "t": "Peptide vs amino-acid absorption", "d": "Most digestion products are absorbed as di-/tripeptides by secondary active transport coupled to a H⁺ gradient; free amino acids are absorbed by secondary active transport coupled to Na⁺. Absorbed peptides are then hydrolyzed to amino acids inside the cell, which exit basolaterally by facilitated diffusion. (Note: unlike carbohydrates, where only monosaccharides are absorbed, small peptides can be absorbed intact.)", "topic": "Protein digestion and absorption", "citation": "Vander's 16e Ch 15 §15.6 'Protein' (p.558): 'Most of the products of protein digestion are absorbed as short chains of two or three amino acids by secondary active transport coupled to the H+ gradient... Free amino acids... enter the epithelial cells by secondary active transport coupled to Na+... Within the cytosol of the epithelial cell, the dipeptides and tripeptides are hydrolyzed to amino acids; these... then leave the cell and enter the interstitial fluid through facilitated-diffusion transporters in the basolateral membranes.'", "corrected": false }, { "t": "Saliva: composition and control", "d": "Secreted by three pairs of glands (parotid, sublingual, submandibular); contains mucus, water, HCO₃⁻ (buffers acid), lysozyme (antibacterial), and amylase + lipase (minor digestion). Both sympathetic and parasympathetic neurons stimulate secretion (parasympathetic dominant) — there is no hormonal control; per gram of tissue it is the body's largest exocrine secretion.", "topic": "Mouth, pharynx, esophagus: saliva and swallowing", "citation": "Vander's 16e Ch 15 §15.4 'Saliva' (p.542-543, Table 15.3): 'Saliva is secreted through a series of short ducts from three pairs of salivary glands—the parotid, sublingual, and submandibular glands. It contains mucus, water, HCO3−, and several enzymes... Saliva also contains amylase and lipase... salivary lysozyme, an antibacterial enzyme... controlled by both sympathetic and parasympathetic neurons... both systems stimulate salivary secretion, with the parasympathetic neurons producing the greater response. There is no hormonal regulation... the volume of saliva secreted per gram of tissue is the largest secretion of any of the body's exocrine glands.'", "corrected": false }, { "t": "Swallowing reflex", "d": "A complex reflex triggered when pressure receptors in the pharynx are stimulated by food pushed back by the tongue; afferents go to the swallowing center in the medulla oblongata, which drives efferents to pharyngeal, esophageal, and respiratory muscles. Because both skeletal and smooth muscle are involved, the center uses both somatic and autonomic nerves; the soft palate elevates and the epiglottis covers the glottis to prevent aspiration.", "topic": "Mouth, pharynx, esophagus: saliva and swallowing", "citation": "Vander's 16e Ch 15 §15.4 'Swallowing' (p.543-544): 'Swallowing is a complex reflex initiated when pressure receptors in the walls of the pharynx are stimulated by food or drink forced into the rear of the mouth by the tongue. These receptors send afferent impulses to the swallowing center in the medulla oblongata of the brainstem. This center then elicits swallowing via efferent fibers to the muscles in the pharynx and esophagus as well as to the respiratory muscles... Both skeletal and smooth muscles are involved, so the swallowing center must direct efferent activity in both somatic nerves... and autonomic nerves... the epiglottis... cover[s] the glottis... This prevents aspiration of food.'", "corrected": false }, { "t": "Esophageal sphincters and peristalsis", "d": "The upper esophageal sphincter is skeletal muscle; the lower esophageal sphincter is smooth muscle and normally stays closed to prevent gastric reflux. Food is moved to the stomach by peristalsis (a progressive wave of contraction, ~9 s), not gravity — so swallowing works even upside down. A retained bolus distends the esophagus and triggers secondary peristalsis.", "topic": "Mouth, pharynx, esophagus: saliva and swallowing", "citation": "Vander's 16e Ch 15 §15.4 'Esophagus' (p.543-544): 'A ring of skeletal muscle surrounds the esophagus just below the pharynx and forms the upper esophageal sphincter, whereas the smooth muscle in the last portion of the esophagus forms the lower esophageal sphincter... Each esophageal peristaltic wave takes about 9 seconds to reach the stomach. Swallowing can occur even when a person is upside down or in zero gravity... if a large food bolus does not reach the stomach during the initial peristaltic wave, the maintained distension... initiate[s] reflexes, causing repeated waves of peristaltic activity (secondary peristalsis).'", "corrected": false }, { "t": "Pancreatic exocrine secretions", "d": "The exocrine pancreas secretes HCO₃⁻ (neutralizes duodenal acid) plus digestive enzymes: proteases (trypsin, chymotrypsin, elastase, carboxypeptidase), lipase (fats), amylase (polysaccharides), and ribonuclease/deoxyribonuclease (nucleic acids). Secretion rises during a meal mainly via secretin (→ HCO₃⁻) and CCK (→ enzymes).", "topic": "Pancreatic secretions and zymogen activation", "citation": "Vander's 16e Ch 15 §15.6 'Pancreatic Secretions' (p.553-554, Table 15.5): 'Enzymes secreted by the pancreas digest fat, polysaccharides, proteins, and nucleic acids... Trypsin, chymotrypsin, elastase... Carboxypeptidase... Lipase... Amylase... Ribonuclease, deoxyribonuclease... Pancreatic secretion increases during a meal, mainly as a result of stimulation... by the hormones secretin and CCK... Secretin is the primary stimulant for HCO3− secretion, whereas CCK mainly stimulates acinar cell [enzyme] secretion.'", "corrected": false }, { "t": "Zymogen activation (enterokinase → trypsin)", "d": "Pancreatic proteases are secreted as inactive zymogens (preventing autodigestion). Enterokinase, bound to the intestinal brush-border membrane, cleaves trypsinogen to active trypsin; trypsin then activates the other pancreatic zymogens (e.g., chymotrypsinogen, procarboxypeptidase). Non-proteolytic enzymes (amylase, lipase) are secreted already active.", "topic": "Pancreatic secretions and zymogen activation", "citation": "Vander's 16e Ch 15 §15.6 (p.554, Fig 15.23): 'The proteolytic enzymes are secreted in inactive forms (zymogens)... Like pepsinogen, the secretion of zymogens protects pancreatic cells from autodigestion. A key step... is mediated by enterokinase, which is embedded in the apical plasma membranes of the intestinal epithelial cells. Enterokinase is a proteolytic enzyme that splits off a peptide from pancreatic trypsinogen, forming the active enzyme trypsin... it activates the other pancreatic zymogens... The nonproteolytic enzymes secreted by the pancreas (e.g., amylase and lipase) are released in fully active form.'", "corrected": false }, { "t": "Vitamin B12 absorption and pernicious anemia", "d": "Vitamin B12 is a large charged molecule that must bind intrinsic factor (secreted by gastric parietal cells); the IF–B12 complex is absorbed by endocytosis in the lower ileum. Loss of intrinsic factor (autoimmune destruction of parietal cells, gastrectomy) or ileal disease causes pernicious anemia, since B12 is needed for erythrocyte formation; treatment is usually B12 injections.", "topic": "Vitamin B12 absorption via intrinsic factor", "citation": "Vander's 16e Ch 15 §15.6 'Vitamins' (p.561): 'vitamin B12 (cyanocobalamin), is a very large, charged molecule. To be absorbed, vitamin B12 must first bind to a protein known as intrinsic factor, which... is secreted by the parietal cells in the stomach. Intrinsic factor with bound vitamin B12 then binds to specific sites on the epithelial cells in the lower portion of the ileum, where vitamin B12 is absorbed by endocytosis... deficiencies result in pernicious anemia... usually requires injections of vitamin B12.'", "corrected": false }, { "t": "Control of HCl secretion", "d": "Three messengers stimulate parietal-cell acid secretion (by inserting H⁺/K⁺-ATPase into the apical membrane): gastrin (hormone), acetylcholine (neurotransmitter), and histamine (paracrine); somatostatin (paracrine) inhibits it. Histamine potentiates the gastrin and ACh responses, and luminal H⁺ provides negative feedback (directly inhibiting gastrin and stimulating somatostatin).", "topic": "Regulation of gastric acid secretion and GI phases", "citation": "Vander's 16e Ch 15 §15.5 'HCl Production and Secretion' (p.546-547, Figs 15.11-15.13): 'Three chemical messengers stimulate the insertion of H+/K+-ATPases into the plasma membrane, thereby increasing acid secretion: gastrin... acetylcholine... and histamine... By contrast, somatostatin... inhibits acid secretion... histamine markedly potentiates the response to the other two stimuli, gastrin and ACh... H+ (acid) directly inhibits gastrin secretion. It also stimulates the release of somatostatin from D cells.'", "corrected": false }, { "t": "Three phases of GI control", "d": "Neural/hormonal control is divided by where the stimulus is sensed: cephalic phase (sight, smell, taste, chewing → vagal parasympathetic output); gastric phase (distension, acid, peptides, amino acids → short/long reflexes + gastrin); intestinal phase (duodenal distension, acidity, osmolarity, digestion products → reflexes + secretin, CCK, GIP). Phases are named for the stimulus site, not the effector, and overlap in time.", "topic": "Regulation of gastric acid secretion and GI phases", "citation": "Vander's 16e Ch 15 §15.3 'Phases of Gastrointestinal Control' (p.541-542): 'divisible into three phases—cephalic, gastric, and intestinal—according to where the stimulus is perceived. The cephalic phase is initiated when sensory receptors in the head are stimulated by sight, smell, taste, and chewing... mediated by parasympathetic neurons carried in the vagus nerves. Four stimuli in the stomach initiate... the gastric phase: distension, acidity, amino acids, and peptides... mediated by... gastrin. The intestinal phase is initiated by stimuli in the small intestine including distension, acidity, osmolarity... mediated by... secretin, CCK, and GIP... named for the site at which the various stimuli initiate the reflex and not for the sites of effector activity.'", "corrected": false }, { "t": "Gastric phase stimuli of acid secretion", "d": "Once food reaches the stomach, the gastric-phase stimuli that drive increased acid (and pepsinogen) secretion are distension, peptides, and amino acids (products of protein digestion). Importantly, a FALLING H⁺ concentration (rising pH) also promotes acid secretion: dietary protein buffers luminal H⁺, and this drop in acidity removes the H⁺-mediated inhibition of acid secretion. Responses are mediated by short/long neural reflexes and gastrin release. (Note: in §15.3 the four gastric-phase stimuli are listed as distension, acidity, amino acids, and peptides — but the mechanism by which protein raises acid output is precisely that protein lowers H⁺, removing inhibition; do not state that high luminal acidity stimulates the gastric phase, since high H⁺ inhibits it.)", "topic": "Regulation of gastric acid secretion and GI phases", "citation": "Vander's 16e Ch 15 §15.5 (p.548, Table 15.4): 'Gastric contents (gastric phase): Distension, ↑ Peptides, ↓ H+ concentration → Long and short neural reflexes and direct stimulation of gastrin secretion → ↑ HCl secretion.' p.547-548: 'The protein in food is an excellent buffer, so as it enters the stomach, the H+ concentration decreases... This decrease in acidity removes the inhibition of acid secretion. The more protein in a meal... the more acid secreted.'", "corrected": true } ], "resp": [ { "t": "Three forms of CO₂ transport in blood", "d": "CO₂ is carried as: bicarbonate (HCO₃⁻, ~60–65% — the principal form), carbaminohemoglobin (CO₂ bound to Hb amino groups, ~25–30%), and dissolved CO₂ in plasma/cytosol (~10%). Deoxyhemoglobin binds CO₂ more readily, aiding loading in the tissues.", "topic": "Transport of CO2 as bicarbonate (carbonic anhydrase reaction + chloride shift)", "citation": "Vander 16e Ch13, Section 13.7 (13_respiratory_physiology.txt L3805–3821): 'only about 10% of the carbon dioxide entering the blood dissolves in the plasma and the cytosol of the erythrocytes ... Another 25% to 30% of the carbon dioxide molecules ... form carbaminohemoglobin ... The remaining 60% to 65% of the carbon dioxide molecules ... is converted to HCO3− ... deoxyhemoglobin ... has a greater affinity for carbon dioxide than does oxyhemoglobin'", "corrected": false }, { "t": "Carbonic anhydrase / bicarbonate pathway (CO₂ loading)", "d": "In erythrocytes, CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺. The first (hydration) step is rate-limiting and is catalyzed by carbonic anhydrase, present in red cells but not plasma, so most conversion occurs inside erythrocytes. This is the main route by which CO₂ is carried and is the source of the H⁺ that makes venous blood more acidic.", "topic": "Transport of CO2 as bicarbonate (carbonic anhydrase reaction + chloride shift)", "citation": "Vander 16e Ch13, Section 13.7 (13_respiratory_physiology.txt L3834–3848): 'The first reaction in equation 13–11 is rate limiting and is very slow unless catalyzed in both directions by the enzyme carbonic anhydrase. This enzyme is present in the erythrocytes but not in the plasma, so this reaction occurs mainly in the erythrocytes ... the H+ concentration in tissue capillary blood and systemic venous blood is higher than that in arterial blood'", "corrected": false }, { "t": "Chloride shift", "d": "After HCO₃⁻ is generated inside the erythrocyte, most of it exits into plasma via a band-3 antiporter that exchanges one HCO₃⁻ out for one Cl⁻ in. This maintains electroneutrality and keeps the carbonic anhydrase reaction running forward. The process reverses in the lung capillaries as CO₂ is unloaded.", "topic": "Transport of CO2 as bicarbonate (carbonic anhydrase reaction + chloride shift)", "citation": "Vander 16e Ch13, Section 13.7 (13_respiratory_physiology.txt L3839–3843): 'most of the HCO3− moves out of the erythrocytes into the plasma via a transporter that exchanges one HCO3− for one chloride ion (this is called the \"chloride shift,\" which maintains electroneutrality). HCO3− leaving the erythrocyte favors the balance of the reaction ... to the right' (Vander does not name band-3, but the band-3/AE1 anion exchanger is the established identity of this transporter — Costanzo Physiology 7e; StatPearls 'Biochemistry, Chloride')", "corrected": false }, { "t": "Boyle's law (applied to ventilation)", "d": "At constant temperature, the pressure of a fixed quantity of gas is inversely proportional to its volume (P₁V₁ = P₂V₂). Respiratory muscles change lung (alveolar) volume; by Boyle's law this changes alveolar pressure, which is what drives air flow in (inspiration) or out (expiration).", "topic": "Boyle's law and the intrapleural-pressure mechanism that drives airflow during the respiratory cycle", "citation": "Vander 16e Ch13, Section 13.2 (13_respiratory_physiology.txt L760–773): 'Boyle's law: The pressure exerted by a constant number of gas molecules (at a constant temperature) is inversely proportional to the volume of the container ... the volume of the \"container\"—the lungs—is made to change, and these changes then cause, by Boyle's law, the alveolar pressure changes that drive airflow into or out of the lungs'", "corrected": false }, { "t": "Subatmospheric intrapleural pressure (and pneumothorax)", "d": "The intrapleural pressure (Pip) is subatmospheric (\"negative\") because the elastic lung recoils inward while the chest wall recoils outward. This creates the transpulmonary pressure (Ptp = Palv − Pip) that holds the lungs open. If the seal is broken (pneumothorax), air enters the pleural space, Pip rises toward atmospheric, Ptp falls, and the lung collapses.", "topic": "Boyle's law and the intrapleural-pressure mechanism that drives airflow during the respiratory cycle", "citation": "Vander 16e Ch13, Section 13.2 (13_respiratory_physiology.txt L949–961, L790): 'the elastic recoil of both the lungs and chest wall creates the subatmospheric intrapleural pressure ... Atmospheric air enters the intrapleural space through the wound, a phenomenon called pneumothorax, and the intrapleural pressure increases from −4 mmHg to 0 mmHg ... The transpulmonary pressure acting to hold the lung open is eliminated, and the lung collapses' and 'Ptp = Palv − Pip' (eq 13–3)", "corrected": false }, { "t": "Hypoxia (definition + four categories)", "d": "Hypoxia = a deficiency of oxygen at the tissue level. Four categories: (1) Hypoxic hypoxia (hypoxemia) — low arterial PO₂; (2) Anemic/CO hypoxia — normal PO₂ but reduced O₂-carrying capacity; (3) Ischemic (hypoperfusion) hypoxia — inadequate blood flow; (4) Histotoxic hypoxia — adequate O₂ delivery but cells cannot use it (e.g., cyanide).", "topic": "Hypoxia and its categories (hypoxic, anemic, ischemic, histotoxic; CO poisoning)", "citation": "Vander 16e Ch13, Section 13.10 (13_respiratory_physiology.txt L5020–5107): 'Hypoxia is defined as a deficiency of oxygen at the tissue level ... classified into four general categories: Hypoxic hypoxia (also termed hypoxemia): arterial PO2 is reduced; Anemic hypoxia or carbon monoxide hypoxia ...; Ischemic hypoxia (also called hypoperfusion hypoxia) ...; Histotoxic hypoxia: ... a toxic agent—cyanide, for example'", "corrected": false }, { "t": "Anemic vs histotoxic hypoxia (key contrast)", "d": "Anemic (and carbon-monoxide) hypoxia: arterial PO₂ is normal but total O₂ content is low because of too few RBCs, abnormal/deficient Hb, or CO occupying O₂-binding sites. Histotoxic hypoxia: O₂ delivery to tissue is normal but a toxin (e.g., cyanide) blocks the cell's ability to use O₂ for oxidative metabolism.", "topic": "Hypoxia and its categories (hypoxic, anemic, ischemic, histotoxic; CO poisoning)", "citation": "Vander 16e Ch13, Section 13.10 (13_respiratory_physiology.txt L5096–5107): 'Anemic hypoxia or carbon monoxide hypoxia: arterial PO2 is normal but the total oxygen content of the blood is decreased because of inadequate numbers of erythrocytes, deficient or abnormal hemoglobin, or competition for the hemoglobin molecule by carbon monoxide ... Histotoxic hypoxia: quantity of oxygen reaching the tissues is normal but the cell is unable to utilize the oxygen because a toxic agent—cyanide, for example'", "corrected": false }, { "t": "O₂ therapy caution in chronic hypercapnia", "d": "In patients whose chronic lung disease causes both hypoxia and CO₂ retention (hypercapnia), the reflex ventilatory drive from high PCO₂ may be blunted, leaving hypoxia as the primary respiratory drive. Giving 100% O₂ can remove that drive and cause them to stop breathing, so they are treated with an air/O₂ mixture rather than pure oxygen.", "topic": "Hypoxia and its categories (hypoxic, anemic, ischemic, histotoxic; CO poisoning)", "citation": "Vander 16e Ch13, Section 13.10 (13_respiratory_physiology.txt L5114–5124): 'some of the diseases that produce hypoxia also produce carbon dioxide retention and an increased arterial PCO2 (hypercapnia) ... The primary respiratory drive in such patients is the hypoxia, because for several reasons the reflex ventilatory response to an increased PCO2 may be lost in chronic situations. The administration of pure oxygen may cause such patients to stop breathing; consequently, such individuals are typically treated with a mixture of air and oxygen rather than 100% oxygen'", "corrected": false }, { "t": "Respiratory rhythm generator (medullary centers)", "d": "The basic breathing rhythm originates in the medullary respiratory center: the dorsal respiratory group (DRG) drives inspiratory spinal motor neurons (e.g., phrenic nerve → diaphragm), while the ventral respiratory group (VRG) contains the rhythm generator in the pre-Bötzinger complex (pacemaker cells + neural network) plus expiratory neurons used during active/forced expiration.", "topic": "Respiratory rhythm generation / brainstem respiratory centers (medullary dorsal & ventral respiratory groups, pre-Botzinger complex, pontine centers)", "citation": "Vander 16e Ch13, Section 13.9 (13_respiratory_physiology.txt L4150–4167): 'The neurons of the dorsal respiratory group (DRG) primarily fire during inspiration and have input to the spinal motor neurons that activate respiratory muscles involved in inspiration—the diaphragm ... innervated by the phrenic nerves. The ventral respiratory group (VRG) ... The respiratory rhythm generator is located in the pre-Bötzinger complex of neurons in the upper part of the VRG ... composed of pacemaker cells and a complex neural network ... The VRG contains expiratory neurons that appear to be most important when large increases in ventilation are required'", "corrected": false }, { "t": "Pontine respiratory centers & Hering–Breuer reflex", "d": "The pons fine-tunes medullary output via two centers. The apneustic center (lower pons) fine-tunes the medullary inspiratory neurons and helps terminate inspiration. The pneumotaxic center (= pontine respiratory group, upper pons) modulates the apneustic center and helps smooth the transition between inspiration and expiration (aided by afferent input about lung inflation). Separately, the Hering–Breuer reflex is a cutoff in which pulmonary stretch receptors, activated by large lung inflation, send afferents that inhibit medullary inspiratory neurons to prevent overinflation.", "topic": "Respiratory rhythm generation / brainstem respiratory centers (medullary dorsal & ventral respiratory groups, pre-Botzinger complex, pontine centers)", "citation": "Vander 16e Ch13, Section 13.9 (13_respiratory_physiology.txt L4177–4191, and summary box L5038–5042): '... an area of the lower pons called the apneustic center is the major source of this output [that fine-tunes the medullary inspiratory neurons and may help terminate inspiration], whereas an area of the upper pons called the pneumotaxic center modulates the activity of the apneustic center. The pneumotaxic center, also known as the pontine respiratory group, helps to smooth the transition between inspiration and expiration ... pulmonary stretch receptors ... inhibit the activity of the medullary inspiratory neurons. This is called the Hering–Breuer reflex.' Summary box: 'Apneustic center: fine-tunes activity of the medullary inspiratory neurons and helps terminate inspiration; Pneumotaxic center ...: modulates activity of apneustic center; helps to smooth transitions between inspiration and expiration'", "corrected": true } ], "renal": [ { "t": "Acidosis vs alkalosis (definitions)", "d": "Acidosis = arterial plasma H+ raised, pH < 7.4 (H+ gain exceeds loss); alkalosis = arterial plasma H+ lowered, pH > 7.4 (loss exceeds gain). Normal ECF pH is 7.35-7.45; values outside 6.8-7.8 are incompatible with life. H+ matters because it alters the tertiary structure (and thus function) of proteins/enzymes.", "topic": "Hydrogen ion regulation / acid-base balance", "citation": "Vander 16e Ch14 §14.16: 'When loss exceeds gain, the arterial plasma H+ concentration decreases and pH exceeds 7.4. This is termed alkalosis. When gain exceeds loss...pH is less than 7.4. This is termed acidosis' (L4523-4527); tertiary-structure point L4468-4470 ('influence that H+ has on the tertiary structures of proteins, such as enzymes'). pH range 7.35-7.45 and lethal limits 6.8-7.8 confirmed by StatPearls Physiology, Acid Base Balance (NBK507807) and OpenStax A&P 2e §26.5 (Vander Ch14 itself uses pH 7.4 as the reference, not a range).", "corrected": false }, { "t": "Sources of H+ gain and loss", "d": "Gain: CO2 (volatile acid) generating H+; nonvolatile acids from protein/organic metabolism (phosphoric, sulfuric, lactic; ~40-80 mmol/day net); and loss of HCO3- in diarrhea or in urine (losing HCO3- = gaining H+). Loss: metabolism of organic anions, vomiting (loss of gastric H+), urinary H+ (as H2PO4- and NH4+), and hyperventilation (CO2 loss).", "topic": "Hydrogen ion regulation / acid-base balance", "citation": "Vander 16e Ch14 Table 14.6 (L4488-4501): Gain = 'Generation of H+ from CO2; Production of nonvolatile acids...; Gain of H+ due to loss of HCO3- in diarrhea...; Gain of H+ due to loss of HCO3- in the urine'; Loss = 'Utilization of H+ in the metabolism of various organic anions; Loss of H+ in vomitus; Loss of H+ (primarily in the form of H2PO4- and NH4+) in the urine.' Net 40-80 mmol H+/day at L4560-4561; hyperventilation as CO2/H+ loss at L4548-4550.", "corrected": false }, { "t": "Volatile vs nonvolatile acids", "d": "Volatile acid = CO2: CO2 + H2O ⇌(carbonic anhydrase) H2CO3 ⇌ HCO3- + H+; the H+ made in tissues is reincorporated into water at the lungs and CO2 is exhaled, so no net gain. Nonvolatile (fixed) acids = phosphoric and sulfuric acid (from protein, including sulfur amino acids cysteine/methionine) plus lactic acid; these are eliminated by the kidneys.", "topic": "Hydrogen ion regulation / acid-base balance", "citation": "Vander 16e Ch14 §14.16 eqn 14-1 (L4534-4546): 'CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+...the H+ generated via these reactions is reincorporated into water when the reactions are reversed during the passage of blood through the lungs.' Nonvolatile acids: 'They include phosphoric acid and sulfuric acid, generated mainly by the catabolism of proteins, as well as lactic acid' (L4551-4555).", "corrected": false }, { "t": "Buffers (and the major buffer systems)", "d": "A buffer is any substance that reversibly binds H+ (Buffer + H+ ⇌ HBuffer), minimizing changes in H+ concentration; it locks H+ up but does not add/remove it from the body. Major extracellular buffer system = CO2/HCO3-; major intracellular buffers = proteins (e.g., hemoglobin) and phosphates.", "topic": "Hydrogen ion regulation / acid-base balance", "citation": "Vander 16e Ch14 §14.17 (L4599-4624): 'Any substance that can reversibly bind H+ is called a buffer'; 'Buffer + H+ ⇌ HBuffer'; 'The major extracellular buffer is the CO2/HCO3- system...the major intracellular buffers are phosphates and proteins. An example of an intracellular protein buffer is hemoglobin'; 'This buffering does not eliminate H+ from the body or add it to the body; it only keeps the H+ locked up' (L4625-4626).", "corrected": false }, { "t": "Kidneys vs lungs in acid-base balance (timing)", "d": "Both regulate plasma H+. The respiratory response is fast (minutes): rising H+ stimulates ventilation, lowering PCO2 and (by mass action) H+; falling H+ inhibits ventilation. The kidneys are slow (hours-days) but are the ultimate balancers, normally excreting the H+ from nonvolatile acids. If the lungs cause the imbalance, the kidney is the sole compensator, and vice versa.", "topic": "Hydrogen ion regulation / acid-base balance", "citation": "Vander 16e Ch14 §14.17-14.18 (L4639-4645): 'The respiratory response to altered plasma H+ concentration is very rapid (minutes)...until the more slowly responding kidneys (hours to days) can actually eliminate the imbalance. If the respiratory system is the actual cause of the H+ imbalance, then the kidneys are the sole homeostatic responder. Conversely, malfunctioning kidneys can create an imbalance...and then the respiratory response is the only one in control.' Kidneys 'ultimately responsible' / 'normally excrete the excess H+ from nonvolatile acids' L4672-4675.", "corrected": false }, { "t": "Renal HCO3- handling (acidosis vs alkalosis response)", "d": "The kidney controls plasma H+ by adjusting plasma HCO3-. HCO3- is freely filtered; its 'reabsorption' is indirect, depending on tubular H+ secretion (intracellular CO2+H2O→H+ + HCO3-; secreted H+ combines with luminal HCO3-). Normally ALL filtered HCO3- is reabsorbed. In alkalosis the kidney excretes HCO3- (alkaline urine); in acidosis it reabsorbs all HCO3- and adds new HCO3- to plasma.", "topic": "Hydrogen ion regulation / acid-base balance (renal HCO3- handling)", "citation": "Vander 16e Ch14 §14.19 (L4706-4810, Fig 14.33): 'HCO3- reabsorption depends on the tubular secretion of H+, which combines in the lumen with filtered HCO3-' (L4745-4746); 'the kidneys normally reabsorb all filtered HCO3-' (L4810); 'When the plasma H+...decreases (alkalosis)...the kidneys'...response is to excrete large quantities of HCO3-...In contrast, when plasma H+...increases (acidosis), the kidneys do not excrete HCO3-...tubular cells produce new HCO3- and add it to the plasma' (L4724-4729). Alkaline urine in alkalosis confirmed Table 14.7 'urine is alkaline (pH > 7.4).'", "corrected": false }, { "t": "Generating NEW HCO3- (phosphate buffer + glutamine/ammonium)", "d": "Once all filtered HCO3- is reabsorbed, additional secreted H+ binds a nonbicarbonate buffer (mainly HPO4²-, excreted as H2PO4-), and the HCO3- made in the cell is now NET-new HCO3- added to plasma. A second route: proximal-tubule cells metabolize glutamine to NH4+ + HCO3-; NH4+ is secreted (Na+/NH4+ countertransport) and excreted while the new HCO3- enters blood. Urinary H+ excretion ≈ new HCO3- added.", "topic": "Hydrogen ion regulation / acid-base balance (renal HCO3- handling)", "citation": "Vander 16e Ch14 §14.19 (L4819-4882, Figs 14.34-14.35): 'the extra secreted H+ combines in the lumen with a filtered nonbicarbonate buffer, the most important of which is HPO42-. The H+ is then excreted...as part of H2PO4-...the HCO3- generated within the tubular cell...constitutes a net gain of HCO3- by the plasma' (L4819-4824); 'Tubular cells, mainly those of the proximal tubule, take up glutamine...both NH4+ and HCO3- are formed inside the cells. The NH4+ is secreted via Na+/NH4+ countertransport...the HCO3- moves into the peritubular capillaries' (L4835-4839); 'urinary H+ excretion and renal contribution of new HCO3-...are really two sides of the same coin' (L4877-4879).", "corrected": false }, { "t": "Classification: respiratory vs metabolic acidosis/alkalosis", "d": "Respiratory = primary change in alveolar ventilation: respiratory acidosis (hypoventilation/CO2 retention) raises both PCO2 and H+; respiratory alkalosis (hyperventilation) lowers both — PCO2 and H+ move together. Metabolic = any nonrespiratory cause (e.g., metabolic acidosis from lactic acid, ketoacids, diarrhea; metabolic alkalosis from vomiting); compensatory ventilation makes PCO2 and H+ move in OPPOSITE directions. In acidosis the kidney can drive urine to a minimum pH of ~4.4.", "topic": "Hydrogen ion regulation / acid-base balance (classification)", "citation": "Vander 16e Ch14 §14.20 (L4980-5008, Tables 14.7-14.8): 'The hallmark of respiratory acidosis is an increase in both arterial PCO2 and H+ concentration, whereas that of respiratory alkalosis is a decrease in both'; 'in metabolic as opposed to respiratory conditions, the arterial plasma PCO2 and H+ concentration move in opposite directions' (L5007-5008). Causes: lactic acid/ketones/diarrhea (acidosis), persistent vomiting (alkalosis) L5093-5101. Minimum urine pH: 'The urine is highly acidic (lowest attainable pH = 4.4)' Table 14.7 (L5023-5024).", "corrected": false }, { "t": "Potassium balance & hyper/hypokalemia", "d": "K+ is the most abundant intracellular ion (only ~2% of body K+ is extracellular), and the K+ gradient sets the resting membrane potential of nerve and muscle. Hyperkalemia (raised) and hypokalemia (lowered) plasma K+ both cause cardiac arrhythmias and abnormal skeletal-muscle and nerve conduction. Steady-state balance = urinary K+ excretion matches intake minus fecal/sweat losses; urinary excretion is the major regulator.", "topic": "Potassium regulation", "citation": "Vander 16e Ch14 §14.12 (L4057-4071): 'Potassium is the most abundant intracellular ion. Although only 2% of total-body potassium is in the extracellular fluid...the resting membrane potentials of these tissues largely depend on the concentration gradient of K+...either increases (hyperkalemia) or decreases (hypokalemia) in extracellular K+ concentration can cause abnormal rhythms of the heart (arrhythmias) and abnormalities of skeletal muscle contraction and neuronal action potential conduction'; steady-state balance = 'excreting an amount of K+ in the urine equal to the amount ingested minus the amounts eliminated in feces and sweat...The control of urinary K+ excretion is the major mechanism' (L4065-4071).", "corrected": false }, { "t": "Renal K+ handling — secretion in the cortical collecting duct", "d": "K+ is freely filtered and most filtered K+ is reabsorbed earlier; the regulated variable is K+ SECRETION by the cortical collecting duct. There, basolateral Na+/K+-ATPase pumps K+ into the cell and it diffuses into the lumen through apical K+ channels — coupled to Na+ reabsorption in that segment. During K+ depletion, collecting-duct secretion stops and only the small unreabsorbed filtered K+ is excreted.", "topic": "Potassium regulation", "citation": "Vander 16e Ch14 §14.12 'Renal Regulation of K+' (L4075-4139, Fig 14.30): 'K+ is freely filterable...the tubules reabsorb most of this filtered K+...the cortical collecting ducts can secrete K+ and changes in K+ excretion are due mainly to changes in K+ secretion by this tubular segment'; 'the K+ pumped into the cell across the basolateral membrane by Na+/K+-ATPases diffuses into the tubular lumen through K+ channels in the apical membrane...the secretion of K+ by the cortical collecting duct is associated with the reabsorption of Na+' (L4128-4131); during depletion 'there is no K+ secretion by the cortical collecting ducts. Only the small amount of filtered K+ that escapes tubular reabsorption is excreted' (L4080-4082).", "corrected": false }, { "t": "Control of K+ secretion: plasma K+ and aldosterone", "d": "Two main drivers of cortical-collecting-duct K+ secretion: (1) plasma K+ itself — a high-K+ diet raises plasma K+ slightly, directly stimulating basolateral Na+/K+-ATPase uptake and thus secretion; (2) aldosterone — high extracellular K+ directly stimulates adrenal-cortex aldosterone secretion (independent of renin/angiotensin), and aldosterone enhances both Na+ reabsorption and K+ secretion. Low K+ does the reverse.", "topic": "Potassium regulation", "citation": "Vander 16e Ch14 §14.12 (L4140-4166, Figs 14.31-14.32): 'When a high-potassium diet is ingested...plasma K+ concentration increases, though very slightly, and this directly drives enhanced basolateral uptake via the Na+/K+-ATPase pumps. Thus, there is an enhanced K+ secretion'; 'aldosterone...simultaneously enhances K+ secretion'; 'The aldosterone-secreting cells of the adrenal cortex are sensitive to the K+ concentration of the extracellular fluid...an increased intake of potassium leads to an increased extracellular K+ concentration, which in turn directly stimulates the adrenal cortex to produce aldosterone' — explicitly 'different from the mechanism...involving the renin-angiotensin system' (L4156-4163).", "corrected": false }, { "t": "Internal (transcellular) K+ shifts", "d": "Acutely, a K+ load is buffered by shifting K+ into cells (mainly skeletal muscle) via Na+/K+-ATPase, stimulated by insulin and catecholamines (epinephrine), preventing dangerous hyperkalemia until the kidney slowly excretes it. Acidosis shifts K+ OUT of cells (raising plasma K+ → hyperkalemia); alkalosis shifts K+ into cells (hypokalemia).", "topic": "Potassium regulation", "citation": "Not covered in Vander 16e Ch14 (this chapter addresses only renal/external K+ handling). Corroborated by StatPearls Hypokalemia (NBK482465) and UpToDate 'Potassium balance in acid-base disorders': insulin, aldosterone, and beta-adrenergic (epinephrine) stimulation promote cellular K+ uptake (lowering plasma K+); 'an increase in plasma H+ (acidosis) causes...K+ movement out of cells,' whereas metabolic alkalosis stimulates cellular K+ uptake.", "corrected": false }, { "t": "Renal Ca²⁺ regulation by PTH", "d": "~60% of plasma Ca²⁺ is filterable (rest is protein-bound/complexed). Over 60% of Ca²⁺ reabsorption is hormone-independent in the proximal tubule; hormonal control is in the distal convoluted tubule and early cortical collecting duct. When plasma Ca²⁺ falls, PTH rises and opens Ca²⁺ channels to increase Ca²⁺ reabsorption; PTH also activates renal 1-hydroxylase to make 1,25-(OH)2D, boosting GI Ca²⁺/phosphate absorption.", "topic": "Renal regulation of calcium and phosphate", "citation": "Vander 16e Ch14 §14.13 (L4288-4304): 'Approximately 60% of plasma calcium is available for filtration...The remaining plasma calcium is protein-bound or complexed with anions...More than 60% of calcium ion reabsorption is not under hormonal control and occurs in the proximal tubule. The hormonal control...occurs mainly in the distal convoluted tubule and early in the cortical collecting duct. When plasma calcium is low, the secretion of parathyroid hormone (PTH)...increases. PTH stimulates the opening of calcium channels...increasing calcium ion reabsorption...PTH...increase[s] the activity of the 1-hydroxylase enzyme, thus activating 25(OH)-D to 1,25-(OH)2D, which then goes on to increase calcium and phosphate ion absorption in the gastrointestinal tract' (L4232-4237).", "corrected": false }, { "t": "Renal phosphate handling and PTH (vs calcium)", "d": "About half of plasma phosphate is ionized and filterable; like Ca²⁺ most filtered phosphate is reabsorbed in the proximal tubule. Opposite to its effect on Ca²⁺, PTH DECREASES phosphate reabsorption, increasing phosphate excretion. So when plasma Ca²⁺ is low (PTH high), Ca²⁺ reabsorption rises while phosphate excretion rises.", "topic": "Renal regulation of calcium and phosphate", "citation": "Vander 16e Ch14 §14.13 (L4238-4242): 'About half of the plasma phosphate is ionized and is filterable. Like calcium, most of the phosphate ion that is filtered is reabsorbed in the proximal tubule. Unlike calcium ion, phosphate ion reabsorption is decreased by PTH, thereby increasing the excretion of phosphate ion. Therefore, when plasma calcium is low, and PTH and calcium ion reabsorption are increased as a result, phosphate ion excretion is increased.'", "corrected": false }, { "t": "Diuretics — general mechanism & classes", "d": "Diuretics increase urine volume, most by inhibiting tubular Na+ (and Cl-/HCO3-) reabsorption so water reabsorption falls. Classes by nephron site: loop diuretics (e.g., furosemide) block NKCC in the thick ascending limb; potassium-sparing diuretics act in the cortical collecting duct, either blocking aldosterone (spironolactone, eplerenone) or the epithelial Na+ channel (triamterene, amiloride); osmotic diuretics (e.g., mannitol) are filtered but not reabsorbed, holding water in the tubule.", "topic": "Diuretics", "citation": "Vander 16e Ch14 §14.15 (L4396-4458): 'Most act on the tubules to inhibit the reabsorption of Na+, along with Cl- and/or HCO3-...water reabsorption is also reduced'; 'loop diuretics, such as furosemide, act on the ascending limb of the loop of Henle to inhibit...cotransport of Na+ and Cl- by the NKCC'; 'potassium-sparing diuretics inhibit Na+ reabsorption in the cortical collecting duct...either block the action of aldosterone (e.g., spironolactone or eplerenone) or block the epithelial Na+ channel...(e.g., triamterene or amiloride). Osmotic diuretics such as mannitol are filtered but not reabsorbed, thus retaining water in the urine.'", "corrected": false }, { "t": "Loop diuretics and K+ loss (clinical link)", "d": "Loop diuretics (furosemide) inhibit NKCC in the ascending limb, increasing Na+ and water excretion — but the extra Na+ delivered downstream drives increased K+ secretion in the cortical collecting duct, causing hypokalemia. Potassium-sparing diuretics avoid this. Used in edema (congestive heart failure) and hypertension; diuretic overuse can produce metabolic alkalosis.", "topic": "Diuretics", "citation": "Vander 16e Ch14 §14.15 (L4408-4439): 'Loop diuretics can have the unwanted side effect of causing low plasma K+. Due to increased Na+ delivery to the distal nephrons, K+ secretion can increase in the cortical collecting ducts...This can lead to the loss of K+ in the urine'; potassium-sparing diuretics 'do not cause increased K+ excretion' (L4414-4415); edema/CHF and hypertension uses (L4428-4439). Diuretic overuse → metabolic alkalosis is Vander Ch14 end-of-chapter Question 13 (L5747-5748, 'How can the overuse of diuretics lead to metabolic alkalosis?'); mechanism (contraction alkalosis) corroborated by Medscape Metabolic Alkalosis and Sica 2004 J Clin Hypertension.", "corrected": false } ], "endo": [ { "t": "Absorptive state", "d": "The period during and after a meal when nutrients are being digested/absorbed; net synthesis of glycogen, triglyceride, and protein. Energy is supplied mainly by absorbed glucose, and excess glucose/amino acids are stored as glycogen and fat. Driven by high insulin.", "topic": "Absorptive vs postabsorptive metabolic states", "citation": "Vander's 16e Ch 16, S&R 16.1: 'Absorptive state: period when nutrients are being digested and absorbed and there is net synthesis of glycogen, triglyceride, and protein... energy provided primarily by absorbed carbohydrate; some carbohydrate used for synthesis of glycogen and fat... absorbed amino acids used to synthesize proteins; excess amino acids used to synthesize carbohydrate and triglycerides.' Insulin secretion 'is increased during the absorptive state.'", "corrected": false }, { "t": "Postabsorptive state", "d": "The fasting period when the GI tract is empty; net breakdown of glycogen, fat, and protein. Blood glucose is maintained by hepatic glycogenolysis and gluconeogenesis, while most tissues switch to oxidizing fatty acids and ketones. Driven by low insulin and high glucagon.", "topic": "Absorptive vs postabsorptive metabolic states", "citation": "Vander's 16e Ch 16, S&R 16.1: 'Postabsorptive state: period when nutrients are no longer being digested or absorbed, and there is net breakdown of glycogen, fat, and protein... glucose concentration in blood maintained by hepatic glycogenolysis and gluconeogenesis, and a switch to fatty acid and ketone utilization by most tissues.' Plus: 'during the postabsorptive state, there is an increase in the glucagon/insulin ratio in the plasma.'", "corrected": false }, { "t": "Glucose sparing (postabsorptive)", "d": "In fasting, most tissues oxidize fatty acids (from adipose lipolysis) and ketones for energy instead of glucose, sparing the limited glucose for the brain and nervous system. The brain's GLUT is insulin-independent, so neurons keep taking up glucose even when insulin is low.", "topic": "Absorptive vs postabsorptive metabolic states", "citation": "Vander's 16e Ch 16, S&R 16.1: 'Glucose sparing: Most of the body's energy supply comes from oxidation of fatty acids released by adipose-tissue lipolysis, and from ketones produced by the liver; this spares glucose for the brain and nervous system.' On brain GLUT: 'the cells of the brain express a different subtype of GLUT, one that has very high affinity for glucose and whose activity is not insulin-dependent... even if the plasma insulin concentration is very low, as in prolonged fasting, cells of the brain can continue to take up glucose.'", "corrected": false }, { "t": "Sources of plasma glucose in fasting", "d": "Two hepatic processes maintain blood glucose postabsorptively: (1) glycogenolysis -- breakdown of stored liver glycogen; (2) gluconeogenesis -- synthesis of new glucose from lactate, pyruvate, glycerol, and amino acids. The kidneys also perform gluconeogenesis during a prolonged fast.", "topic": "Absorptive vs postabsorptive metabolic states", "citation": "Vander's 16e Ch 16, Summary of Nutrient Metabolism During the Postabsorptive State: 'Glucose is formed in the liver both from the glycogen stored there and by gluconeogenesis from blood-borne lactate, pyruvate, glycerol, and amino acids. The kidneys also perform gluconeogenesis during a prolonged fast.'", "corrected": false }, { "t": "Ketone bodies (ketogenesis)", "d": "Acidic molecules the liver produces from fatty acids during the postabsorptive state (and starvation/uncontrolled diabetes). Most tissues oxidize them for energy, and as they accumulate the brain begins using them too, further sparing glucose. Glucagon stimulates hepatic ketone synthesis.", "topic": "Absorptive vs postabsorptive metabolic states", "citation": "Vander's 16e Ch 16: 'most of the acetyl CoA it [liver] forms from fatty acids during the postabsorptive state... is processed into three compounds collectively called ketones, or ketone bodies... an important energy source during prolonged fasting for many tissues, including those of the nervous system... the brain can use ketones for an energy source, and it does so increasingly as ketones build up.' Glucagon 'stimulates the synthesis of ketones' (in the liver). Diabetic ketoacidosis section: 'Two ketones, known as [beta-]hydroxybutyric acid and [acetoacetic acid]' confirms ketones are acids.", "corrected": false }, { "t": "Thermoregulation", "d": "Homeostatic control of core body temperature by balancing heat production against heat loss; humans are endotherms (generate their own heat) and homeotherms (temperature stays within narrow limits). The hypothalamus is the integrating center, using input from peripheral and central thermoreceptors. Heat is exchanged with the environment by radiation, conduction, convection, and evaporation.", "topic": "Regulation of body temperature (thermoregulation) and fever", "citation": "Vander's 16e Ch 16, S&R 16.6: 'Thermoregulation: process in which body temperature is maintained within a homeostatic range... Humans are endotherms (generate their own body heat) and homeotherms (body temperature does not fluctuate except within narrow limits)... The body exchanges heat with the external environment by radiation, conduction, convection, and evaporation... Integrating centers for temperature-regulating reflexes are located in the hypothalamus; both peripheral and central thermoreceptors participate.'", "corrected": false }, { "t": "Heat production vs heat loss responses", "d": "In cold: skin vasoconstriction reduces heat loss, and increased muscle tone/shivering thermogenesis raises heat production. In heat: skin vasodilation increases heat loss and, above the thermoneutral zone, sweating (evaporative cooling) becomes essential. The thermoneutral zone is the temperature range in which vasomotor changes alone maintain body temperature.", "topic": "Regulation of body temperature (thermoregulation) and fever", "citation": "Vander's 16e Ch 16, S&R 16.6: 'Heat production: increased by increasing muscle tone, shivering thermogenesis, and voluntary activity; essential for temperature regulation at environmental temperatures below the thermoneutral zone (the range of external temperatures in which changes in skin vasodilation or vasoconstriction are sufficient to maintain body temperature). Heat loss: depends on the temperature difference between the skin surface and the environment; sweating is essential at temperatures above the thermoneutral zone.'", "corrected": false }, { "t": "Fever", "d": "An increase in core temperature caused by resetting the hypothalamic 'thermostat' to a higher set point (usually by infection). Endogenous pyrogens (IL-1β, IL-6, TNF-α from macrophages) trigger hypothalamic prostaglandin synthesis that raises the set point; the body then shivers and vasoconstricts to reach it. Aspirin lowers fever by inhibiting prostaglandin synthesis.", "topic": "Regulation of body temperature (thermoregulation) and fever", "citation": "Vander's 16e Ch 16: 'Fever is an increase in core body temperature due to a resetting of the \"thermostat\" in the hypothalamus... at a higher set point. The most common cause of fever is infection... endogenous pyrogen (EP) are released from macrophages... the immediate cause of the resetting is a local synthesis and release of prostaglandins within the hypothalamus. Aspirin reduces fever by inhibiting this prostaglandin synthesis... interleukin 1-beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNFα)... function as EPs.' Vasoconstriction and shivering occur to drive temperature to the new set point.", "corrected": false }, { "t": "Hyperthermia vs fever", "d": "Hyperthermia is a rise in body temperature WITHOUT a change in set point (set point is normal); fever is a rise WITH an elevated set point. The most common hyperthermia is exercise, where heat produced by muscles outpaces heat loss. Severe forms: heat exhaustion (collapse/fainting from sweating-induced hypotension) and heatstroke (breakdown of heat-loss control; a dangerous positive-feedback rise; sweating stops).", "topic": "Regulation of body temperature (thermoregulation) and fever", "citation": "Vander's 16e Ch 16: 'When body temperature is increased for any other reason... but without a change in the temperature set point, it is termed hyperthermia. The most common cause of hyperthermia in a typical person is exercise; the increase in body temperature above set point is due to the internal heat generated by the exercising muscles... Heat exhaustion is a state of collapse, often taking the form of fainting, due to hypotension brought on by depletion of plasma volume secondary to sweating and extreme dilation of skin blood vessels... heatstroke represents a complete breakdown in heat-regulating systems... the person eventually stops sweating. Heatstroke is a harmful positive feedback situation in which the increasing body temperature directly stimulates metabolism.'", "corrected": false }, { "t": "Counterregulatory (glucose-counterregulatory) hormones", "d": "The hormones that oppose insulin to raise blood glucose: glucagon, epinephrine, cortisol, and growth hormone. They are released in response to hypoglycemia and sympathetic (stress) activation and collectively promote glycogenolysis, gluconeogenesis, lipolysis, and inhibition of glucose uptake by muscle/adipose. Insulin is the primary regulatory hormone; these are its physiological antagonists.", "topic": "Counterregulatory hormones opposing insulin", "citation": "Vander's 16e Ch 16, chapter intro: 'the primary regulatory hormone insulin and the counterregulatory hormones cortisol, growth hormone, glucagon, and epinephrine.' S&R 16.2: 'Counterregulation: the actions of hormones that oppose those of insulin; major stimuli for release include hypoglycemia and the SNS.' Table 16.4 'Summary of Glucose-Counterregulatory Controls' lists Glucagon, Epinephrine, Cortisol, Growth Hormone across Glycogenolysis, Gluconeogenesis, Lipolysis, and Inhibition of glucose uptake by muscle/adipose.", "corrected": false }, { "t": "Epinephrine (metabolic effects)", "d": "Adrenal-medulla catecholamine and a counterregulatory hormone: stimulates glycogenolysis in BOTH liver and skeletal muscle, gluconeogenesis in the liver, and lipolysis in adipocytes (by activating hormone-sensitive lipase). Net effect is to raise plasma glucose and fatty acids; it also increases metabolic rate.", "topic": "Counterregulatory hormones opposing insulin", "citation": "Vander's 16e Ch 16, S&R 16.2: 'Epinephrine (from adrenal medulla): stimulates glycogenolysis in the liver and muscle, gluconeogenesis in the liver, and lipolysis in adipocytes (via activation of hormone-sensitive lipase, HSL).' Table 16.4 footnote: 'Epinephrine stimulates glycogenolysis in both the liver and skeletal muscle, whereas glucagon does so only in the liver.' Epinephrine section: 'Epinephrine is another hormone that exerts a calorigenic effect... the metabolic rate increases.'", "corrected": false }, { "t": "Metabolic rate & total energy expenditure", "d": "Metabolic rate is total energy expenditure per unit time. By the first law of thermodynamics, energy released from catabolized nutrients = internal heat produced + external work performed + energy stored. About 60% of released energy appears immediately as heat. Energy is commonly measured in kilocalories (kcal; 1 food Calorie = 1 kcal).", "topic": "Regulation of total-body energy balance and metabolic rate", "citation": "Vander's 16e Ch 16: 'During metabolism, about 60% of the energy released from organic molecules appears immediately as heat, and the rest is used for work... Total energy expenditure = Internal heat produced + External work performed + Energy stored... In the field of nutrition, one food calorie is equivalent to one kilocalorie... Total energy expenditure per unit time is called the metabolic rate.'", "corrected": false }, { "t": "Basal metabolic rate (BMR)", "d": "Metabolic rate measured under standardized basal conditions: awake, at rest, at a comfortable temperature, and postabsorptive (fasted ≥12 h) -- the 'metabolic cost of living.' The single most important determinant of BMR is thyroid hormone (T3), whose calorigenic effect raises O2 consumption and heat production in most tissues; epinephrine and leptin also raise it.", "topic": "Regulation of total-body energy balance and metabolic rate", "citation": "Vander's 16e Ch 16: 'In the basal condition, the subject is at rest in a room at a comfortable temperature and has not eaten for at least 12 h (i.e., is in the postabsorptive state)... The BMR is sometimes called the \"metabolic cost of living.\"' And: 'The active thyroid hormone, T3, is the most important determinant of BMR regardless of body size, age, or gender. T3 increases the oxygen consumption and heat production of most body tissues, a notable exception being the brain. This ability to increase BMR is known as a calorigenic effect.' Epinephrine 'exerts a calorigenic effect'; 'Leptin also increases BMR.'", "corrected": false }, { "t": "Leptin & energy balance", "d": "Peptide hormone secreted by adipocytes in proportion to fat stores; it signals total-body energy content to the hypothalamus, decreasing food intake (partly by inhibiting neuropeptide Y) and increasing BMR. Falling leptin (weight loss/starvation) stimulates appetite and conserves energy. Most obesity reflects leptin RESISTANCE (leptin levels are high, not low), analogous to insulin resistance.", "topic": "Regulation of total-body energy balance and metabolic rate", "citation": "Vander's 16e Ch 16: 'the polypeptide hormone leptin, synthesized by adipocytes and released from the cells in proportion to the amount of fat they contain. This hormone acts on the hypothalamus to cause a decrease in food intake, in part by inhibiting the release of neuropeptide Y... Leptin also increases BMR.' On obesity: 'The leptin secreted by these individuals is normal, and leptin concentrations in the blood are increased, not decreased... such people are leptin-resistant in much the same way that people with type 2 diabetes mellitus are insulin-resistant.'", "corrected": false } ], "repro": [ { "t": "Leydig cells", "d": "Interstitial cells of the testis stimulated by LH to synthesize and secrete testosterone. Testosterone then feeds back to inhibit LH (and GnRH) secretion.", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17: 'Leydig cells: synthesize and release testosterone' (L1786); 'LH...acts primarily on the Leydig cells to stimulate testosterone secretion' (L1963-1965); 'Testosterone inhibits LH secretion...acts on the hypothalamus to decrease the amplitude of GnRH bursts' (L1974, L2014-2018)", "corrected": false }, { "t": "Sertoli cells", "d": "Seminiferous-tubule support cells stimulated by FSH (and testosterone) that nourish developing sperm, form the blood-testis barrier, secrete androgen-binding protein and inhibin, and (in the fetus) AMH.", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17, Table 17.2 'Functions of Sertoli Cells' (L1746-1759): blood-testes barrier, nourish sperm, secrete luminal fluid incl ABP, respond to testosterone and FSH, secrete inhibin, secrete AMH; 'AMH...causes the primordial female duct system to regress during embryonic life'", "corrected": false }, { "t": "FSH vs LH targets in the male", "d": "FSH acts only on Sertoli cells (supporting spermatogenesis and inhibin release); LH acts primarily on Leydig cells (driving testosterone secretion).", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17, Fig 17.14 caption (L2105): 'FSH acts only on the Sertoli cells, whereas LH acts primarily on the Leydig cells.'", "corrected": false }, { "t": "Inhibin (male)", "d": "Protein hormone secreted by Sertoli cells in response to FSH; exerts selective negative feedback on FSH secretion from the anterior pituitary (without affecting LH).", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17: 'The major inhibitory signal, exerted directly on the anterior pituitary gland, is the protein hormone inhibin secreted by the Sertoli cells...FSH stimulates Sertoli cells to increase both spermatogenesis and inhibin production, and inhibin decreases FSH release' (L2020-2024); Fig 17.14 'secretion of FSH is inhibited mainly by inhibin' (L2107)", "corrected": false }, { "t": "Male reproductive negative feedback", "d": "Dual loop: testosterone (from Leydig cells) inhibits mainly LH/GnRH, while inhibin (from Sertoli cells) selectively inhibits FSH. Thus FSH and LH can be controlled somewhat independently.", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17: 'Even though FSH and LH are produced by the same cell type, their secretion rates can be altered to different degrees by negative feedback inputs' (L1972-1973); S&R 17.8 'testosterone: inhibits both the hypothalamus and the anterior pituitary gland to (mainly) decrease LH secretion; inhibin: exerts negative feedback on FSH secretion' (L2188-2190)", "corrected": false }, { "t": "Androgen-binding protein (ABP)", "d": "Protein secreted by Sertoli cells into the seminiferous-tubule lumen that binds testosterone, maintaining a high local androgen concentration needed to sustain spermatogenesis.", "topic": "17.8 Hormonal control of male reproductive function", "citation": "Vander's 16e Ch 17: 'This fluid contains androgen-binding protein (ABP) that binds the testosterone secreted by the Leydig cells...This protein maintains a high concentration of total testosterone in the lumen of the tubule' (L1721-1725); S&R 17.6 'androgen-binding protein that maintains high local testosterone concentration to stimulate development of spermatocytes' (L1781-1783)", "corrected": false }, { "t": "Ovarian follicle", "d": "Fluid-filled ovarian structure containing an oocyte plus surrounding granulosa cells (inner) and theca cells (outer); the functional unit of the ovary for both oogenesis and sex-steroid secretion.", "topic": "17.13 Ovarian function & folliculogenesis", "citation": "Vander's 16e Ch 17: 'Follicle: fluid-filled structure within the ovaries containing an egg and associated structures' (L2930-2932); 'the inner layer of granulosa cells remains closely associated with the oocyte' (L2730-2731); 'connective-tissue cells surrounding the granulosa cells differentiate and form layers of cells known as the theca' (L2734-2735)", "corrected": false }, { "t": "Granulosa vs theca cells", "d": "Theca cells synthesize androgens (estrogen precursors); granulosa cells convert those androgens to estrogen via aromatase and also secrete inhibin and the zona pellucida — the female analogues of Leydig and Sertoli cells.", "topic": "17.13 Ovarian function & folliculogenesis", "citation": "Vander's 16e Ch 17, S&R 17.13: 'Granulosa cells: synthesize estrogen and inhibin; Theca cells: synthesize androgen (precursor for estrogen synthesis); Zona pellucida: thick surrounding layer secreted by granulosa cells' (L2934-2938); 'The granulosa cell is similar to the Sertoli cell...The theca cell is similar to the Leydig cell' (L3267-3271)", "corrected": false }, { "t": "Two-cell, two-gonadotropin estrogen synthesis", "d": "LH stimulates theca cells to make androgens, which diffuse into granulosa cells where FSH-induced aromatase converts them to estrogen — neither cell type alone can make estrogen.", "topic": "17.13/17.14 Ovarian function & folliculogenesis", "citation": "Vander's 16e Ch 17: 'LH acts upon the theca cells, stimulating them...to synthesize androgens. The androgens diffuse into the granulosa cells and are converted to estrogen by aromatase' (L3230-3232); 'the secretion of estrogen by the granulosa cells requires the interplay of both types of follicle cells and both pituitary gland gonadotropins' (L3262-3264)", "corrected": false }, { "t": "Folliculogenesis sequence", "d": "Primordial follicle → preantral/early antral follicles → a single dominant follicle (others undergo atresia) → mature Graafian follicle → ovulation → corpus luteum. The egg sits in the cumulus oophorus.", "topic": "17.13 Ovarian function & folliculogenesis", "citation": "Vander's 16e Ch 17, S&R 17.13 steps 1-5: 'Primordial follicles start to mature...preantral and early antral follicles develop...Only the dominant follicle continues...other developing follicles die (atresia); the egg is surrounded by cumulus oophorus...Graafian follicle (fully mature)...the corpus luteum' (L2944-2954)", "corrected": false }, { "t": "Follicular vs luteal phase", "d": "The ovarian cycle is split by ovulation: in the follicular phase the dominant follicle matures and estrogen dominates; in the luteal phase the corpus luteum forms and progesterone dominates.", "topic": "17.13/17.14 Ovarian function & folliculogenesis", "citation": "Vander's 16e Ch 17, S&R 17.13: 'Two phases of the ovarian cycle separated by ovulation...Follicular phase: mature follicle and secondary oocyte develop; estrogen dominates. Luteal phase: corpus luteum forms; progesterone dominates' (L2955-2961)", "corrected": false }, { "t": "Estrogen positive feedback (LH surge)", "d": "Late-follicular high, rapidly rising estrogen switches from negative to POSITIVE feedback, sensitizing the pituitary to GnRH (via kisspeptin) and triggering the midcycle LH surge that causes ovulation. The key positive-feedback loop of the cycle.", "topic": "17.14 Control of ovarian function", "citation": "Vander's 16e Ch 17: increasing estrogen 'act upon the anterior pituitary gland to enhance the sensitivity of gonadotropin-releasing cells to GnRH...and also stimulates GnRH release...may be mediated by activation of kisspeptin neurons...a particularly important example of positive feedback...rapidly increasing estrogen leads to the LH surge' (L3412-3422)", "corrected": false }, { "t": "Proliferative phase (uterus)", "d": "Uterine phase coinciding with the ovarian follicular phase: estrogen stimulates regrowth of the endometrium and myometrium and thins cervical mucus so sperm can penetrate.", "topic": "17.15 Uterine changes in the menstrual cycle", "citation": "Vander's 16e Ch 17, S&R 17.15: 'Uterine menstrual and proliferative phases: coincide with ovarian follicular phase...Proliferative phase: estrogen stimulates: growth of the endometrium and myometrium (smooth muscle); thinning of the cervical mucus to be readily penetrable by sperm' (L3823-3840)", "corrected": false }, { "t": "Secretory phase (uterus)", "d": "Uterine phase coinciding with the ovarian luteal phase: progesterone converts the estrogen-primed endometrium into secretory tissue, thickens cervical mucus, and inhibits uterine contractions — preparing for implantation.", "topic": "17.15 Uterine changes in the menstrual cycle", "citation": "Vander's 16e Ch 17, S&R 17.15: 'Uterine secretory phase: coincides with ovarian luteal phase...Secretory phase: progesterone predominates and: converts the estrogen-primed endometrium to a secretory tissue; makes the cervical mucus relatively impenetrable to sperm; inhibits uterine contractions' (L3829-3846)", "corrected": false }, { "t": "Menstrual phase / menstruation", "d": "Day 1 of the cycle: regression of the corpus luteum drops estrogen and progesterone, causing spiral-artery vasoconstriction and degeneration of the endometrium with menstrual flow.", "topic": "17.15 Uterine changes in the menstrual cycle", "citation": "Vander's 16e Ch 17, S&R 17.15: 'Menstruation: first day of the cycle...Menstruation: due to decrease in plasma estrogen and progesterone concentrations (regression of the corpus luteum); vasoconstriction of uterine spiral arteries' (L3827-3833); 'The first event is constriction of the uterine blood vessels' (L3799)", "corrected": false }, { "t": "Physiology of erection", "d": "Parasympathetic (nonadrenergic, noncholinergic) neurons and endothelium release nitric oxide, which raises cGMP and relaxes penile arterial smooth muscle; engorgement of the vascular compartments compresses draining veins, producing rigidity.", "topic": "17.7 Male sexual response (erection)", "citation": "Vander's 16e Ch 17: 'activation of nonadrenergic, noncholinergic autonomic neurons...These neurons and associated endothelial cells release nitric oxide, which relaxes the arterial smooth muscle' (L1853-1855); 'Nitric oxide stimulates the enzyme guanylyl cyclase, which catalyzes the formation of cyclic GMP (cGMP)' (L1892-1893); 'the adjacent veins emptying them are passively compressed' (L1846)", "corrected": false }, { "t": "PDE5 inhibitors (sildenafil)", "d": "Drugs (Viagra, Cialis) that block phosphodiesterase type 5, the enzyme that breaks down cGMP; the resulting higher cGMP prolongs NO-mediated arterial relaxation and erection.", "topic": "17.7 Male sexual response (erection)", "citation": "Vander's 16e Ch 17: 'cGMP-phosphodiesterase type 5 (PDE5) inhibitors including sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis)...The sequence of events is terminated by an enzyme-dependent breakdown of cGMP. PDE5 inhibitors block the action of this enzyme and thereby permit a higher concentration of cGMP to exist' (L1890-1898)", "corrected": false }, { "t": "Ejaculation (emission vs expulsion)", "d": "A spinal reflex with two phases: (1) emission — sympathetic contraction of epididymis, vas deferens, ejaculatory ducts, prostate, and seminal vesicles loads sperm and secretions into the urethra; (2) expulsion of ~3 mL semen by rhythmic urethral smooth-muscle and pelvic skeletal-muscle contractions.", "topic": "17.7 Sperm transport & male sexual response", "citation": "Vander's 16e Ch 17: 'Ejaculation is primarily a spinal reflex' (L1903); '(1) The smooth muscles of the epididymis, vas deferens, ejaculatory ducts, prostate, and seminal vesicles contract as a result of sympathetic nerve stimulation...(emission). (2) Semen, with an average volume of 3 mL...is then expelled from the urethra by a series of rapid contractions of the urethral smooth muscle as well as the skeletal muscle at the base of the penis' (L1924-1933)", "corrected": true }, { "t": "Puberty onset (kisspeptin)", "d": "Puberty begins when the amplitude and frequency of GnRH pulses rise — driven by activation of hypothalamic kisspeptin neurons — increasing FSH/LH and gonadal steroids; the brain also becomes less sensitive to steroid negative feedback.", "topic": "17.9 / 17.17 Puberty", "citation": "Vander's 16e Ch 17 (male): 'The amplitude and pulse frequency of GnRH secretion increase at puberty, probably stimulated by input from kisspeptin neurons...the brain becomes less sensitive to the negative feedback effects of gonadal hormones at the time of puberty' (L2218-2229); (female) 'activation of kisspeptin neurons in the hypothalamus is involved in the increase in GnRH that occurs early in puberty' (L3976-3977)", "corrected": false }, { "t": "Menarche", "d": "The first menstruation, a late event of female puberty marking maturation of the hypothalamo-pituitary-ovarian axis; influenced by body fat via the adipose hormone leptin.", "topic": "17.17 Puberty (Female)", "citation": "Vander's 16e Ch 17: 'Menarche, the first menstruation, is a late event of puberty (averaging about 12.5 years of age in the United States)' (L3981-3983); 'the adipose-tissue hormone leptin...is known to stimulate the secretion of GnRH and may contribute to the onset of puberty...why the onset of puberty tends to correlate with' body fat (L3987-3989)", "corrected": true }, { "t": "Menopause", "d": "Permanent cessation of menstrual cycles (when the absence exceeds 12 months) due to ovarian failure as follicles are depleted by atresia. Estrogen and inhibin fall, so FSH/LH rise; low estrogen causes vaginal atrophy, hot flashes, and bone loss (osteoporosis).", "topic": "17.19 Menopause", "citation": "Vander's 16e Ch 17: 'menstrual cycles cease entirely...when this period exceeds 12 months, this cessation is known as menopause' (L4116-4117); 'caused primarily by ovarian failure...most, if not all, ovarian follicles and eggs have disappeared by this time through atresia...the decrease in the plasma concentrations of estrogen and inhibin result in less negative feedback inhibition of gonadotropin secretion' (L4121-4128); 'Thinning and dryness of the vaginal epithelium...significant decreases in bone mass may occur (osteoporosis)' (L4132-4134); 'hot flashes' (L4094)", "corrected": false } ], "cell": [ { "t": "Cytoskeleton", "d": "Non-membrane-bound organelle composed of protein filaments; the only organelles without a phospholipid bilayer are the cytoskeleton and ribosomes. General functions: maintain cell shape, hold organelles in position, and mediate cell and organelle motility.", "topic": "Cytoskeleton (microfilaments/actin, intermediate filaments, microtubules/tubulin)", "citation": "Study Notes- Cell Physiology.txt L220-225 ('Cytoskeleton: o Non-membrane bound organelle (only ribosomes and cytoskeleton have no phospholipid bilayer surrounding them)... General functions: maintain cell shape, maintain the position of organelles in the cell, and mediated cell and organelle motility'); corrob. Vander 16e Ch3 ('the cytoplasm of most cells contains a variety of protein filaments... referred to as the cell's cytoskeleton... associated with processes that maintain and change cell shape and produce cell movements')", "corrected": false }, { "t": "Cytoskeletal filaments (3 types)", "d": "Microfilaments — made of the protein actin; Intermediate filaments — made of many different proteins (form part of desmosomes); Microtubules — made of the protein tubulin.", "topic": "Cytoskeleton (microfilaments/actin, intermediate filaments, microtubules/tubulin)", "citation": "Study Notes- Cell Physiology.txt L226-231 ('Microfilaments – made of the protein actin; Intermediate filaments – many different proteins act as intermediate filaments (intermediate filaments are part of desmosomes); Microtubules – made of the protein tubulin'); corrob. Vander 16e Ch3 ('three classes... (1) actin filaments (also called microfilaments), (2) intermediate filaments... composed of twisted strands of several different proteins, including keratin, desmin, and lamin... in association with desmosomes... (3) microtubules... composed of the protein tubulin')", "corrected": false }, { "t": "Intermediate filaments (function link)", "d": "Cytoskeletal filaments built from various proteins; in the cell they form part of desmosomes, anchoring the adhering junction intracellularly and giving tissues mechanical strength.", "topic": "Cytoskeleton (microfilaments/actin, intermediate filaments, microtubules/tubulin)", "citation": "Study Notes- Cell Physiology.txt L229-230 ('Intermediate filaments – many different proteins act as intermediate filaments (intermediate filaments are part of desmosomes)') and L118-122 (desmosomes 'Made of proteins called: plaques, cadherins, intermediate filaments... Intermediate filaments: anchor cytoplasmic surface of desmosome to components inside cell to provide structural support'); corrob. Vander 16e Ch3 ('They provide considerable strength to cells... most extensively developed in the regions of cells subject to mechanical stress (for example, in association with desmosomes)')", "corrected": false }, { "t": "Receptors that function as enzymes (receptor tyrosine kinases)", "d": "A membrane-bound receptor with binding sites for a chemical messenger plus intrinsic enzyme (kinase) activity within the same protein. The kinase phosphorylates tyrosine amino-acid residues, so these are called receptor tyrosine kinases.", "topic": "Membrane-bound receptors that function as enzymes (receptor tyrosine kinases / enzyme-linked receptors)", "citation": "Study Notes- Cell Physiology.txt L585-592 ('Receptors That Function As Enzymes: A membrane-bound receptor... a receptor component with binding sites for a chemical messenger and intrinsic enzyme activity (intrinsic = within the receptor protein)... Also called receptor tyrosine kinases: the enzyme part of the receptor is a kinase that phosphorylates tyrosine amino acid residues'); corrob. Vander 16e Ch5 ('Other plasma membrane receptors for water-soluble messengers have intrinsic enzyme activity... the great majority specifically phosphorylate tyrosine residues. Consequently, these receptors are known as receptor tyrosine kinases')", "corrected": false }, { "t": "Receptor tyrosine kinase mechanism (autophosphorylation)", "d": "Messenger binding activates the kinase, which autophosphorylates tyrosine residues on the receptor itself (auto = self). The resulting phosphotyrosines serve as docking sites for cytoplasmic proteins; a docked protein is activated by phosphorylation and acts on other proteins to produce the cellular response.", "topic": "Membrane-bound receptors that function as enzymes (receptor tyrosine kinases / enzyme-linked receptors)", "citation": "Study Notes- Cell Physiology.txt L593-601 ('The tyrosine kinase part of receptor autophosphorylates or phosphorylates tyrosine amino acid residues on the receptor (auto = self)... The phosphorylated tyrosines (phosphotyrosines) on the receptor act as docking sites for proteins in the cytoplasm... Once a protein binds to the phosphotyrosines it is activated by phosphorylation, and will bind to other proteins in the cell to eventually produce a response'); corrob. Vander 16e Ch5 ('This results in autophosphorylation of the receptor—that is, the receptor phosphorylates some of its own tyrosine residues. The newly created phosphotyrosines... then serve as docking sites for cytoplasmic proteins')", "corrected": false }, { "t": "Three types of membrane-bound receptors (course)", "d": "(1) Ligand-gated ion-channel receptors — receptor and channel are one protein, fast response; (2) receptors that function as enzymes (receptor tyrosine kinases); (3) G-protein-linked receptors that couple via a G-protein to an effector enzyme or ion channel.", "topic": "Membrane-bound receptors that function as enzymes (receptor tyrosine kinases / enzyme-linked receptors)", "citation": "Study Notes- Cell Physiology.txt L562-563 ('3 types of membrane-bound receptors are channel-, enzyme-, or G-protein-linked receptors'), L572-582 (ligand-gated ion channels, 'fast process as the receptor and ion channel are a single protein'), L585-601 (receptor tyrosine kinases), L606-617 (G-protein linked receptors, link receptor to 'an effector protein, which is an ion channel or an enzyme')", "corrected": false }, { "t": "Driving forces for non-vesicular transport", "d": "A difference in energy across a membrane drives passive movement from high to low energy. Three driving forces: chemical (concentration gradient), electrical (membrane potential), and electrochemical (the combination acting on an ion).", "topic": "Driving forces for transport decomposed as chemical vs electrical vs electrochemical", "citation": "Study Notes- Cell Physiology.txt L311-318 ('A difference in energy across a membrane acts as a driving force... Substances always move from a region of high energy to a region of low energy if allowed to move passively... Driving forces can be chemical, electrical or electrochemical'); corrob. Vander 16e Ch4 ('these two driving forces are considered together as a single, combined electrochemical gradient across a membrane')", "corrected": false }, { "t": "Chemical driving force", "d": "Arises when a substance has different concentrations on the two sides of a membrane. Molecules move passively down the concentration gradient (high → low); the larger the concentration difference, the greater the rate of transport. Applies to charged and uncharged substances alike.", "topic": "Driving forces for transport decomposed as chemical vs electrical vs electrochemical", "citation": "Study Notes- Cell Physiology.txt L319-325 ('There is a chemical driving force when there is a different concentration of a substance on either side of a membrane... Molecules move passively from a high to a low concentration... As the side of the gradient increases, the rate of transport of the substance increases')", "corrected": false }, { "t": "Electrical driving force / membrane potential", "d": "Acts only on charged substances and exists because of the membrane potential — a difference in electrical potential (voltage) across the membrane, i.e. a separation of charge. The membrane potential pushes or pulls a charged solute depending on the solute's charge and the polarity of the membrane.", "topic": "Driving forces for transport decomposed as chemical vs electrical vs electrochemical", "citation": "Study Notes- Cell Physiology.txt L326-337 ('Any substance that is charged will be affected by the electrical driving force... Membrane potential is a difference in the electrical potential or voltage across a cell membrane... Also called a separation of charge across the membrane... The membrane potential will push or pull a charged substance in different directions, depending on the charge on the substance... and the membrane potential'); corrob. Vander 16e Ch4 ('The membrane potential provides an electrical force that can influence the movement of ions through their channels')", "corrected": false }, { "t": "Electrochemical driving force", "d": "The sum of the electrical and chemical driving forces acting on an ion; its net direction depends on the combined direction of the two component forces. Neutral (uncharged) substances are unaffected by the electrical component, so for them the electrochemical force reduces to the chemical gradient alone.", "topic": "Driving forces for transport decomposed as chemical vs electrical vs electrochemical", "citation": "Study Notes- Cell Physiology.txt L338-343 ('The electrochemical driving force is the sum of the electrical and chemical driving forces acting on an ion... Remember: neutral substances are not affected by the electrical driving force... Direction that the electrochemical driving force acts depends on the net direction of the electrical and chemical driving forces'); corrob. Vander 16e Ch4 ('these two driving forces are considered together as a single, combined electrochemical gradient... The net movement... determined by the relative magnitudes of the two opposing forces')", "corrected": false }, { "t": "Channel gating (3 modes)", "d": "Gating is the opening (activation) or closing (deactivation/inactivation) of an ion channel between conducting and non-conducting states. Three modes: voltage-gated (voltage change opens/closes), ligand-gated (ligand binding opens/closes), and mechanically-gated (mechanical stimuli such as cell swelling or stretch open/close).", "topic": "Channel gating (voltage-gated, ligand-gated, mechanically-gated channels)", "citation": "Study Notes- Cell Physiology.txt L461-469 ('Gating refers to the opening (activation) or closing (by deactivation or inactivation) of ion channels. Gating is the process of an ion channel transforming between any of its conducting and non-conducting states. Channels may be: voltage-gated (changes in voltage...), ligand-gating (the binding of a substance or ligand...), or mechanically-gated (mechanical stimuli such as swelling or stretching of a cell...)')", "corrected": false }, { "t": "Calcium as a second messenger (calmodulin)", "d": "A first messenger opens a Ca²⁺-permeable ligand-gated channel or a G-protein-linked Ca²⁺ channel; Ca²⁺ entering from the ECF triggers calcium-induced calcium release from the ER. Rising cytosolic Ca²⁺ binds and activates calmodulin, which activates a calmodulin-dependent protein kinase that phosphorylates proteins to produce the response.", "topic": "Calcium / calmodulin second messenger system", "citation": "Study Notes- Cell Physiology.txt L697-715 ('Calcium may enter the cell from the extracellular fluid... The receptor may be a receptor that is a ligand-gated ion channel... The receptor may be a G-protein linked receptor, which will open a calcium channel... calcium that has entered the cytoplasm from the ECF will bind to receptors on... endoplasmic reticulum... this is called calcium-induced calcium release... Calcium activates calmodulin... Active calmodulin activates a calmodulin-dependent protein kinase. The protein kinase phosphorylates proteins in the cell, producing a response'); corrob. Vander 16e Ch5 Fig 5.11 ('On binding with Ca2+, calmodulin changes shape... activate or inhibit... calmodulin-dependent protein kinases leads, via phosphorylation, to... the cell's ultimate responses')", "corrected": false } ] }; const norm = s => (s||'').toLowerCase().replace(/[^a-z0-9]+/g,' ').trim(); // 1) Register the 3 fixed practice papers in the Exam section (re-sittable, full set). if (Array.isArray(window.EXAMS)) { for (const k of Object.keys(PRACTICE_PAPERS)) { const p = PRACTICE_PAPERS[k]; if (!window.EXAMS.some(e => e.id === p.id)) { window.EXAMS.push({ id:p.id, name:p.name, weight:'practice', mins:p.mins, nQ:p.questions.length, hue:p.hue, cover:p.cover, term:'practice', date:'past paper', fixed:true, desc:p.desc, questions:p.questions }); } } } // 2) Partition: the imported real exam papers stay ONLY in the Exam section (registered above) — // their questions are intentionally NOT folded into general practice, so the highest-quality // exam-origin questions live solely in the exam papers. Only the staged CLASS_QUESTIONS (class // samples, not exam-origin) join the practice bank, skipping stems already present. const QB = window.QUESTIONS || (window.QUESTIONS = {}); const seen = {}; for (const m of Object.keys(QB)) { seen[m] = new Set((QB[m]||[]).map(q => norm(q.q))); } function addQ(mod, q, examTag) { if (!mod) return; QB[mod] = QB[mod] || []; seen[mod] = seen[mod] || new Set(); const key = norm(q.q); if (seen[mod].has(key)) return; seen[mod].add(key); QB[mod].push({ q:q.q, options:q.options, a:q.a, e:q.e || '', src:'course', exam:examTag }); } const CQ = window.CLASS_QUESTIONS || {}; for (const m of Object.keys(CQ)) for (const q of CQ[m]) addQ(m, q, 'class-sample'); // 3) Merge verified coverage-gap flashcards into the curated decks (skip duplicate terms). const FC = window.FLASHCARDS || (window.FLASHCARDS = {}); for (const m of Object.keys(COVERAGE_CARDS)) { FC[m] = FC[m] || []; const have = new Set(FC[m].map(c => norm(c.t))); for (const c of COVERAGE_CARDS[m]) { if (have.has(norm(c.t))) continue; have.add(norm(c.t)); FC[m].push({ t:c.t, d:c.d }); } } window.PRACTICE_PAPERS = PRACTICE_PAPERS; })();