{ "chapter": "Circulation", "count": 100, "answerIndex": "zero-based", "notice": "Original practice items including related concept variants; not official examination questions.", "questions": [ { "id": "ventricle-wall", "chapter": "Circulation", "difficulty": "Standard", "stem": "Why is the left ventricular myocardium thicker than the right ventricular myocardium?", "options": [ "It pumps against greater systemic resistance", "It receives blood from the pulmonary artery", "It opens the tricuspid valve", "It fills from the venae cavae" ], "answer": 0, "explanation": "The systemic circuit presents greater resistance and requires higher pressure than the short pulmonary circuit." }, { "id": "av-valve", "chapter": "Circulation", "difficulty": "Standard", "stem": "At which pressure relationship should an atrioventricular valve open?", "options": [ "Ventricular pressure exceeds arterial pressure", "Atrial pressure exceeds ventricular pressure", "Arterial pressure equals zero", "Ventricular pressure exceeds atrial pressure" ], "answer": 1, "explanation": "AV valves open when atrial pressure becomes greater than ventricular pressure, allowing ventricular filling." }, { "id": "sa-node", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Damage to the sinoatrial node most directly disrupts:", "options": [ "Exchange across capillaries", "Oxygen binding to haemoglobin", "Initiation of the normal heartbeat", "Closing of venous valves in the legs" ], "answer": 2, "explanation": "The sinoatrial node normally acts as the heart's pacemaker and initiates each wave of cardiac excitation." }, { "id": "capillary-wall", "chapter": "Circulation", "difficulty": "Standard", "stem": "The one-cell-thick capillary wall mainly improves exchange by:", "options": [ "Increasing diffusion distance", "Producing red blood cells", "Preventing all pressure loss", "Reducing diffusion distance" ], "answer": 3, "explanation": "A thin wall shortens the diffusion pathway between blood and tissue fluid, increasing exchange efficiency." }, { "id": "circulation-double-circuit-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Blood completes separate pulmonary and systemic circuits. Which outcome follows most directly?", "options": [ "It passes through the heart twice during one full journey", "Its thick elastic wall stretches and recoils", "Backflow is limited when blood pressure is low", "Exchange with tissues occurs efficiently" ], "answer": 0, "explanation": "It passes through the heart twice during one full journey. The right heart sends blood to lungs and the left heart sends it to the body." }, { "id": "circulation-double-circuit-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: it passes through the heart twice during one full journey?", "options": [ "An artery receives high-pressure blood from a ventricle", "Blood completes separate pulmonary and systemic circuits", "A limb vein contains one-way valves", "Blood enters a network of narrow one-cell-thick capillaries" ], "answer": 1, "explanation": "It passes through the heart twice during one full journey. The right heart sends blood to lungs and the left heart sends it to the body." }, { "id": "circulation-double-circuit-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After blood completes separate pulmonary and systemic circuits, which explanation best links the change to its outcome?", "options": [ "Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "Valve cusps close if blood begins moving away from the heart", "The right heart sends blood to lungs and the left heart sends it to the body", "The network provides a large area, short diffusion distance and slower flow" ], "answer": 2, "explanation": "It passes through the heart twice during one full journey. The right heart sends blood to lungs and the left heart sends it to the body." }, { "id": "circulation-artery-wall-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After an artery receives high-pressure blood from a ventricle, which observation is most likely?", "options": [ "Backflow is limited when blood pressure is low", "It carries oxygen efficiently", "Exchange with tissues occurs efficiently", "Its thick elastic wall stretches and recoils" ], "answer": 3, "explanation": "Its thick elastic wall stretches and recoils. Elastic tissue smooths pressure changes while muscle and collagen resist rupture." }, { "id": "circulation-artery-wall-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "A learner records that its thick elastic wall stretches and recoils. Which preceding event best accounts for it?", "options": [ "An artery receives high-pressure blood from a ventricle", "Blood enters a network of narrow one-cell-thick capillaries", "A limb vein contains one-way valves", "A red blood cell has a biconcave shape and no nucleus" ], "answer": 0, "explanation": "Its thick elastic wall stretches and recoils. Elastic tissue smooths pressure changes while muscle and collagen resist rupture." }, { "id": "circulation-artery-wall-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After an artery receives high-pressure blood from a ventricle, which explanation best links the change to its outcome?", "options": [ "Valve cusps close if blood begins moving away from the heart", "Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "The network provides a large area, short diffusion distance and slower flow" ], "answer": 1, "explanation": "Its thick elastic wall stretches and recoils. Elastic tissue smooths pressure changes while muscle and collagen resist rupture." }, { "id": "circulation-artery-wall-integrated", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: an artery receives high-pressure blood from a ventricle?", "options": [ "Exchange with tissues occurs efficiently — The network provides a large area, short diffusion distance and slower flow", "Backflow is limited when blood pressure is low — Valve cusps close if blood begins moving away from the heart", "Its thick elastic wall stretches and recoils — Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "It carries oxygen efficiently — The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin" ], "answer": 2, "explanation": "Its thick elastic wall stretches and recoils. Elastic tissue smooths pressure changes while muscle and collagen resist rupture." }, { "id": "circulation-vein-valve-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "A student models this change: A limb vein contains one-way valves. What should the model predict first?", "options": [ "Exchange with tissues occurs efficiently", "It carries oxygen efficiently", "They aggregate and form an initial haemostatic plug", "Backflow is limited when blood pressure is low" ], "answer": 3, "explanation": "Backflow is limited when blood pressure is low. Valve cusps close if blood begins moving away from the heart." }, { "id": "circulation-vein-valve-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "What is the most likely cause when backflow is limited when blood pressure is low?", "options": [ "A limb vein contains one-way valves", "A red blood cell has a biconcave shape and no nucleus", "Platelets contact exposed collagen at a damaged vessel", "Blood enters a network of narrow one-cell-thick capillaries" ], "answer": 0, "explanation": "Backflow is limited when blood pressure is low. Valve cusps close if blood begins moving away from the heart." }, { "id": "circulation-vein-valve-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After a limb vein contains one-way valves, which explanation best links the change to its outcome?", "options": [ "The network provides a large area, short diffusion distance and slower flow", "Valve cusps close if blood begins moving away from the heart", "The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "Adhesion activates platelets to release signals that recruit additional platelets" ], "answer": 1, "explanation": "Backflow is limited when blood pressure is low. Valve cusps close if blood begins moving away from the heart." }, { "id": "circulation-vein-valve-integrated", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a limb vein contains one-way valves?", "options": [ "Exchange with tissues occurs efficiently — The network provides a large area, short diffusion distance and slower flow", "It carries oxygen efficiently — The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "Backflow is limited when blood pressure is low — Valve cusps close if blood begins moving away from the heart", "They aggregate and form an initial haemostatic plug — Adhesion activates platelets to release signals that recruit additional platelets" ], "answer": 2, "explanation": "Backflow is limited when blood pressure is low. Valve cusps close if blood begins moving away from the heart." }, { "id": "circulation-capillary-exchange-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which immediate result is most consistent with this condition: Blood enters a network of narrow one-cell-thick capillaries?", "options": [ "It carries oxygen efficiently", "They aggregate and form an initial haemostatic plug", "A wave of excitation spreads across both atria", "Exchange with tissues occurs efficiently" ], "answer": 3, "explanation": "Exchange with tissues occurs efficiently. The network provides a large area, short diffusion distance and slower flow." }, { "id": "circulation-capillary-exchange-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which condition would most specifically produce this result: exchange with tissues occurs efficiently?", "options": [ "Blood enters a network of narrow one-cell-thick capillaries", "A red blood cell has a biconcave shape and no nucleus", "Platelets contact exposed collagen at a damaged vessel", "The sinoatrial node spontaneously depolarizes" ], "answer": 0, "explanation": "Exchange with tissues occurs efficiently. The network provides a large area, short diffusion distance and slower flow." }, { "id": "circulation-capillary-exchange-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After blood enters a network of narrow one-cell-thick capillaries, which explanation best links the change to its outcome?", "options": [ "The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "The network provides a large area, short diffusion distance and slower flow", "Adhesion activates platelets to release signals that recruit additional platelets", "Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal" ], "answer": 1, "explanation": "Exchange with tissues occurs efficiently. The network provides a large area, short diffusion distance and slower flow." }, { "id": "circulation-capillary-exchange-integrated", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: blood enters a network of narrow one-cell-thick capillaries?", "options": [ "It carries oxygen efficiently — The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "They aggregate and form an initial haemostatic plug — Adhesion activates platelets to release signals that recruit additional platelets", "Exchange with tissues occurs efficiently — The network provides a large area, short diffusion distance and slower flow", "A wave of excitation spreads across both atria — Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal" ], "answer": 2, "explanation": "Exchange with tissues occurs efficiently. The network provides a large area, short diffusion distance and slower flow." }, { "id": "circulation-red-cell-shape-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "A red blood cell has a biconcave shape and no nucleus. Which outcome follows most directly?", "options": [ "Atria finish contracting before the ventricles begin systole", "They aggregate and form an initial haemostatic plug", "A wave of excitation spreads across both atria", "It carries oxygen efficiently" ], "answer": 3, "explanation": "It carries oxygen efficiently. The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin." }, { "id": "circulation-red-cell-shape-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which change most directly explains this observation: it carries oxygen efficiently?", "options": [ "A red blood cell has a biconcave shape and no nucleus", "Platelets contact exposed collagen at a damaged vessel", "The sinoatrial node spontaneously depolarizes", "Conduction slows briefly at the atrioventricular node" ], "answer": 0, "explanation": "It carries oxygen efficiently. The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin." }, { "id": "circulation-red-cell-shape-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After a red blood cell has a biconcave shape and no nucleus, which explanation best links the change to its outcome?", "options": [ "Adhesion activates platelets to release signals that recruit additional platelets", "The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal", "The delay permits ventricular filling before excitation travels through the bundle of His" ], "answer": 1, "explanation": "It carries oxygen efficiently. The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin." }, { "id": "circulation-red-cell-shape-integrated", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: a red blood cell has a biconcave shape and no nucleus?", "options": [ "They aggregate and form an initial haemostatic plug — Adhesion activates platelets to release signals that recruit additional platelets", "A wave of excitation spreads across both atria — Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal", "It carries oxygen efficiently — The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin", "Atria finish contracting before the ventricles begin systole — The delay permits ventricular filling before excitation travels through the bundle of His" ], "answer": 2, "explanation": "It carries oxygen efficiently. The shape increases surface-to-volume ratio and the lost nucleus leaves more room for haemoglobin." }, { "id": "circulation-platelet-plug-outcome", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After platelets contact exposed collagen at a damaged vessel, which observation is most likely?", "options": [ "A wave of excitation spreads across both atria", "The semilunar valves open", "Atria finish contracting before the ventricles begin systole", "They aggregate and form an initial haemostatic plug" ], "answer": 3, "explanation": "They aggregate and form an initial haemostatic plug. Adhesion activates platelets to release signals that recruit additional platelets." }, { "id": "circulation-platelet-plug-cause", "chapter": "Circulation", "difficulty": "Foundation", "stem": "A learner records that they aggregate and form an initial haemostatic plug. Which preceding event best accounts for it?", "options": [ "Platelets contact exposed collagen at a damaged vessel", "Conduction slows briefly at the atrioventricular node", "The sinoatrial node spontaneously depolarizes", "Ventricular pressure rises above pressure in the aorta and pulmonary artery" ], "answer": 0, "explanation": "They aggregate and form an initial haemostatic plug. Adhesion activates platelets to release signals that recruit additional platelets." }, { "id": "circulation-platelet-plug-mechanism", "chapter": "Circulation", "difficulty": "Foundation", "stem": "After platelets contact exposed collagen at a damaged vessel, which explanation best links the change to its outcome?", "options": [ "Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal", "Adhesion activates platelets to release signals that recruit additional platelets", "The pressure gradient pushes the cusps aside and permits ventricular ejection", "The delay permits ventricular filling before excitation travels through the bundle of His" ], "answer": 1, "explanation": "They aggregate and form an initial haemostatic plug. Adhesion activates platelets to release signals that recruit additional platelets." }, { "id": "circulation-platelet-plug-integrated", "chapter": "Circulation", "difficulty": "Foundation", "stem": "Which paired outcome and explanation best follows from this condition: platelets contact exposed collagen at a damaged vessel?", "options": [ "Atria finish contracting before the ventricles begin systole — The delay permits ventricular filling before excitation travels through the bundle of His", "A wave of excitation spreads across both atria — Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal", "They aggregate and form an initial haemostatic plug — Adhesion activates platelets to release signals that recruit additional platelets", "The semilunar valves open — The pressure gradient pushes the cusps aside and permits ventricular ejection" ], "answer": 2, "explanation": "They aggregate and form an initial haemostatic plug. Adhesion activates platelets to release signals that recruit additional platelets." }, { "id": "circulation-sa-node-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "A student models this change: The sinoatrial node spontaneously depolarizes. What should the model predict first?", "options": [ "Atria finish contracting before the ventricles begin systole", "The semilunar valves open", "Atrioventricular valves close and the first heart sound occurs", "A wave of excitation spreads across both atria" ], "answer": 3, "explanation": "A wave of excitation spreads across both atria. Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal." }, { "id": "circulation-sa-node-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "What is the most likely cause when a wave of excitation spreads across both atria?", "options": [ "The sinoatrial node spontaneously depolarizes", "Ventricular pressure rises above pressure in the aorta and pulmonary artery", "Ventricular pressure exceeds atrial pressure at the start of systole", "Conduction slows briefly at the atrioventricular node" ], "answer": 0, "explanation": "A wave of excitation spreads across both atria. Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal." }, { "id": "circulation-sa-node-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After the sinoatrial node spontaneously depolarizes, which explanation best links the change to its outcome?", "options": [ "The delay permits ventricular filling before excitation travels through the bundle of His", "Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal", "The pressure gradient pushes the cusps aside and permits ventricular ejection", "Reversed pressure lifts the valve cusps while chordae prevent prolapse" ], "answer": 1, "explanation": "A wave of excitation spreads across both atria. Pacemaker cells initiate each heartbeat and atrial gap junctions conduct the signal." }, { "id": "circulation-av-delay-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Conduction slows briefly at the atrioventricular node?", "options": [ "The semilunar valves open", "Atrioventricular valves close and the first heart sound occurs", "Atria finish contracting before the ventricles begin systole", "Cardiac output increases" ], "answer": 2, "explanation": "Atria finish contracting before the ventricles begin systole. The delay permits ventricular filling before excitation travels through the bundle of His." }, { "id": "circulation-av-delay-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: atria finish contracting before the ventricles begin systole?", "options": [ "Heart rate rises while stroke volume remains constant", "Ventricular pressure rises above pressure in the aorta and pulmonary artery", "Ventricular pressure exceeds atrial pressure at the start of systole", "Conduction slows briefly at the atrioventricular node" ], "answer": 3, "explanation": "Atria finish contracting before the ventricles begin systole. The delay permits ventricular filling before excitation travels through the bundle of His." }, { "id": "circulation-av-delay-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After conduction slows briefly at the atrioventricular node, which explanation best links the change to its outcome?", "options": [ "The delay permits ventricular filling before excitation travels through the bundle of His", "The pressure gradient pushes the cusps aside and permits ventricular ejection", "Reversed pressure lifts the valve cusps while chordae prevent prolapse", "Output per minute equals heart rate multiplied by volume ejected per beat" ], "answer": 0, "explanation": "Atria finish contracting before the ventricles begin systole. The delay permits ventricular filling before excitation travels through the bundle of His." }, { "id": "circulation-av-delay-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: conduction slows briefly at the atrioventricular node?", "options": [ "The semilunar valves open — The pressure gradient pushes the cusps aside and permits ventricular ejection", "Atria finish contracting before the ventricles begin systole — The delay permits ventricular filling before excitation travels through the bundle of His", "Atrioventricular valves close and the first heart sound occurs — Reversed pressure lifts the valve cusps while chordae prevent prolapse", "Cardiac output increases — Output per minute equals heart rate multiplied by volume ejected per beat" ], "answer": 1, "explanation": "Atria finish contracting before the ventricles begin systole. The delay permits ventricular filling before excitation travels through the bundle of His." }, { "id": "circulation-semilunar-open-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "Ventricular pressure rises above pressure in the aorta and pulmonary artery. Which outcome follows most directly?", "options": [ "Cardiac output increases", "Atrioventricular valves close and the first heart sound occurs", "The semilunar valves open", "Venous return to the heart increases" ], "answer": 2, "explanation": "The semilunar valves open. The pressure gradient pushes the cusps aside and permits ventricular ejection." }, { "id": "circulation-semilunar-open-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which change most directly explains this observation: the semilunar valves open?", "options": [ "Ventricular pressure exceeds atrial pressure at the start of systole", "Skeletal muscles rhythmically compress limb veins", "Heart rate rises while stroke volume remains constant", "Ventricular pressure rises above pressure in the aorta and pulmonary artery" ], "answer": 3, "explanation": "The semilunar valves open. The pressure gradient pushes the cusps aside and permits ventricular ejection." }, { "id": "circulation-semilunar-open-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After ventricular pressure rises above pressure in the aorta and pulmonary artery, which explanation best links the change to its outcome?", "options": [ "The pressure gradient pushes the cusps aside and permits ventricular ejection", "Output per minute equals heart rate multiplied by volume ejected per beat", "Reversed pressure lifts the valve cusps while chordae prevent prolapse", "One-way valves direct the squeezed blood centrally and prevent reverse movement" ], "answer": 0, "explanation": "The semilunar valves open. The pressure gradient pushes the cusps aside and permits ventricular ejection." }, { "id": "circulation-semilunar-open-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: ventricular pressure rises above pressure in the aorta and pulmonary artery?", "options": [ "Atrioventricular valves close and the first heart sound occurs — Reversed pressure lifts the valve cusps while chordae prevent prolapse", "The semilunar valves open — The pressure gradient pushes the cusps aside and permits ventricular ejection", "Venous return to the heart increases — One-way valves direct the squeezed blood centrally and prevent reverse movement", "Cardiac output increases — Output per minute equals heart rate multiplied by volume ejected per beat" ], "answer": 1, "explanation": "The semilunar valves open. The pressure gradient pushes the cusps aside and permits ventricular ejection." }, { "id": "circulation-av-close-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "After ventricular pressure exceeds atrial pressure at the start of systole, which observation is most likely?", "options": [ "Cardiac output increases", "Venous return to the heart increases", "Atrioventricular valves close and the first heart sound occurs", "Fluid filters from plasma into tissue spaces" ], "answer": 2, "explanation": "Atrioventricular valves close and the first heart sound occurs. Reversed pressure lifts the valve cusps while chordae prevent prolapse." }, { "id": "circulation-av-close-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "A learner records that atrioventricular valves close and the first heart sound occurs. Which preceding event best accounts for it?", "options": [ "Heart rate rises while stroke volume remains constant", "Skeletal muscles rhythmically compress limb veins", "Hydrostatic pressure is high at the arterial end of a capillary", "Ventricular pressure exceeds atrial pressure at the start of systole" ], "answer": 3, "explanation": "Atrioventricular valves close and the first heart sound occurs. Reversed pressure lifts the valve cusps while chordae prevent prolapse." }, { "id": "circulation-av-close-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After ventricular pressure exceeds atrial pressure at the start of systole, which explanation best links the change to its outcome?", "options": [ "Reversed pressure lifts the valve cusps while chordae prevent prolapse", "One-way valves direct the squeezed blood centrally and prevent reverse movement", "Outward pressure exceeds the opposing oncotic and tissue pressures", "Output per minute equals heart rate multiplied by volume ejected per beat" ], "answer": 0, "explanation": "Atrioventricular valves close and the first heart sound occurs. Reversed pressure lifts the valve cusps while chordae prevent prolapse." }, { "id": "circulation-av-close-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: ventricular pressure exceeds atrial pressure at the start of systole?", "options": [ "Cardiac output increases — Output per minute equals heart rate multiplied by volume ejected per beat", "Atrioventricular valves close and the first heart sound occurs — Reversed pressure lifts the valve cusps while chordae prevent prolapse", "Venous return to the heart increases — One-way valves direct the squeezed blood centrally and prevent reverse movement", "Fluid filters from plasma into tissue spaces — Outward pressure exceeds the opposing oncotic and tissue pressures" ], "answer": 1, "explanation": "Atrioventricular valves close and the first heart sound occurs. Reversed pressure lifts the valve cusps while chordae prevent prolapse." }, { "id": "circulation-cardiac-output-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "A student models this change: Heart rate rises while stroke volume remains constant. What should the model predict first?", "options": [ "Venous return to the heart increases", "Fluid filters from plasma into tissue spaces", "Cardiac output increases", "Plasma proteins favour net reabsorption of tissue fluid" ], "answer": 2, "explanation": "Cardiac output increases. Output per minute equals heart rate multiplied by volume ejected per beat." }, { "id": "circulation-cardiac-output-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "What is the most likely cause when cardiac output increases?", "options": [ "Skeletal muscles rhythmically compress limb veins", "Hydrostatic pressure is high at the arterial end of a capillary", "Capillary hydrostatic pressure falls toward the venous end", "Heart rate rises while stroke volume remains constant" ], "answer": 3, "explanation": "Cardiac output increases. Output per minute equals heart rate multiplied by volume ejected per beat." }, { "id": "circulation-cardiac-output-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After heart rate rises while stroke volume remains constant, which explanation best links the change to its outcome?", "options": [ "Output per minute equals heart rate multiplied by volume ejected per beat", "One-way valves direct the squeezed blood centrally and prevent reverse movement", "Outward pressure exceeds the opposing oncotic and tissue pressures", "Protein-generated oncotic pressure becomes greater than the remaining outward pressure" ], "answer": 0, "explanation": "Cardiac output increases. Output per minute equals heart rate multiplied by volume ejected per beat." }, { "id": "circulation-cardiac-output-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: heart rate rises while stroke volume remains constant?", "options": [ "Venous return to the heart increases — One-way valves direct the squeezed blood centrally and prevent reverse movement", "Cardiac output increases — Output per minute equals heart rate multiplied by volume ejected per beat", "Fluid filters from plasma into tissue spaces — Outward pressure exceeds the opposing oncotic and tissue pressures", "Plasma proteins favour net reabsorption of tissue fluid — Protein-generated oncotic pressure becomes greater than the remaining outward pressure" ], "answer": 1, "explanation": "Cardiac output increases. Output per minute equals heart rate multiplied by volume ejected per beat." }, { "id": "circulation-venous-return-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Skeletal muscles rhythmically compress limb veins?", "options": [ "Fluid filters from plasma into tissue spaces", "Plasma proteins favour net reabsorption of tissue fluid", "Venous return to the heart increases", "The fluid and leaked proteins eventually return to the blood" ], "answer": 2, "explanation": "Venous return to the heart increases. One-way valves direct the squeezed blood centrally and prevent reverse movement." }, { "id": "circulation-venous-return-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: venous return to the heart increases?", "options": [ "Excess tissue fluid enters blind-ended lymph capillaries", "Hydrostatic pressure is high at the arterial end of a capillary", "Capillary hydrostatic pressure falls toward the venous end", "Skeletal muscles rhythmically compress limb veins" ], "answer": 3, "explanation": "Venous return to the heart increases. One-way valves direct the squeezed blood centrally and prevent reverse movement." }, { "id": "circulation-venous-return-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After skeletal muscles rhythmically compress limb veins, which explanation best links the change to its outcome?", "options": [ "One-way valves direct the squeezed blood centrally and prevent reverse movement", "Outward pressure exceeds the opposing oncotic and tissue pressures", "Protein-generated oncotic pressure becomes greater than the remaining outward pressure", "Lymph vessels drain through larger ducts into veins near the heart" ], "answer": 0, "explanation": "Venous return to the heart increases. One-way valves direct the squeezed blood centrally and prevent reverse movement." }, { "id": "circulation-venous-return-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: skeletal muscles rhythmically compress limb veins?", "options": [ "Fluid filters from plasma into tissue spaces — Outward pressure exceeds the opposing oncotic and tissue pressures", "Venous return to the heart increases — One-way valves direct the squeezed blood centrally and prevent reverse movement", "Plasma proteins favour net reabsorption of tissue fluid — Protein-generated oncotic pressure becomes greater than the remaining outward pressure", "The fluid and leaked proteins eventually return to the blood — Lymph vessels drain through larger ducts into veins near the heart" ], "answer": 1, "explanation": "Venous return to the heart increases. One-way valves direct the squeezed blood centrally and prevent reverse movement." }, { "id": "circulation-tissue-fluid-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "Hydrostatic pressure is high at the arterial end of a capillary. Which outcome follows most directly?", "options": [ "The fluid and leaked proteins eventually return to the blood", "Plasma proteins favour net reabsorption of tissue fluid", "Fluid filters from plasma into tissue spaces", "Haemoglobin releases oxygen more readily" ], "answer": 2, "explanation": "Fluid filters from plasma into tissue spaces. Outward pressure exceeds the opposing oncotic and tissue pressures." }, { "id": "circulation-tissue-fluid-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which change most directly explains this observation: fluid filters from plasma into tissue spaces?", "options": [ "Capillary hydrostatic pressure falls toward the venous end", "Carbon dioxide and hydrogen-ion concentration rise in active tissue", "Excess tissue fluid enters blind-ended lymph capillaries", "Hydrostatic pressure is high at the arterial end of a capillary" ], "answer": 3, "explanation": "Fluid filters from plasma into tissue spaces. Outward pressure exceeds the opposing oncotic and tissue pressures." }, { "id": "circulation-tissue-fluid-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After hydrostatic pressure is high at the arterial end of a capillary, which explanation best links the change to its outcome?", "options": [ "Outward pressure exceeds the opposing oncotic and tissue pressures", "Lymph vessels drain through larger ducts into veins near the heart", "Protein-generated oncotic pressure becomes greater than the remaining outward pressure", "Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right" ], "answer": 0, "explanation": "Fluid filters from plasma into tissue spaces. Outward pressure exceeds the opposing oncotic and tissue pressures." }, { "id": "circulation-oncotic-return-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "After capillary hydrostatic pressure falls toward the venous end, which observation is most likely?", "options": [ "The fluid and leaked proteins eventually return to the blood", "Plasma proteins favour net reabsorption of tissue fluid", "Haemoglobin releases oxygen more readily", "Part of the cardiac muscle receives less oxygen" ], "answer": 1, "explanation": "Plasma proteins favour net reabsorption of tissue fluid. Protein-generated oncotic pressure becomes greater than the remaining outward pressure." }, { "id": "circulation-oncotic-return-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "A learner records that plasma proteins favour net reabsorption of tissue fluid. Which preceding event best accounts for it?", "options": [ "Excess tissue fluid enters blind-ended lymph capillaries", "Carbon dioxide and hydrogen-ion concentration rise in active tissue", "Capillary hydrostatic pressure falls toward the venous end", "A coronary artery becomes severely narrowed" ], "answer": 2, "explanation": "Plasma proteins favour net reabsorption of tissue fluid. Protein-generated oncotic pressure becomes greater than the remaining outward pressure." }, { "id": "circulation-oncotic-return-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After capillary hydrostatic pressure falls toward the venous end, which explanation best links the change to its outcome?", "options": [ "Lymph vessels drain through larger ducts into veins near the heart", "Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right", "Reduced coronary flow limits aerobic respiration in the myocardium", "Protein-generated oncotic pressure becomes greater than the remaining outward pressure" ], "answer": 3, "explanation": "Plasma proteins favour net reabsorption of tissue fluid. Protein-generated oncotic pressure becomes greater than the remaining outward pressure." }, { "id": "circulation-oncotic-return-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: capillary hydrostatic pressure falls toward the venous end?", "options": [ "Plasma proteins favour net reabsorption of tissue fluid — Protein-generated oncotic pressure becomes greater than the remaining outward pressure", "The fluid and leaked proteins eventually return to the blood — Lymph vessels drain through larger ducts into veins near the heart", "Haemoglobin releases oxygen more readily — Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right", "Part of the cardiac muscle receives less oxygen — Reduced coronary flow limits aerobic respiration in the myocardium" ], "answer": 0, "explanation": "Plasma proteins favour net reabsorption of tissue fluid. Protein-generated oncotic pressure becomes greater than the remaining outward pressure." }, { "id": "circulation-lymph-return-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "A student models this change: Excess tissue fluid enters blind-ended lymph capillaries. What should the model predict first?", "options": [ "Haemoglobin releases oxygen more readily", "The fluid and leaked proteins eventually return to the blood", "Part of the cardiac muscle receives less oxygen", "The left ventricle works harder and vessel walls face greater damage" ], "answer": 1, "explanation": "The fluid and leaked proteins eventually return to the blood. Lymph vessels drain through larger ducts into veins near the heart." }, { "id": "circulation-lymph-return-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "What is the most likely cause when the fluid and leaked proteins eventually return to the blood?", "options": [ "Carbon dioxide and hydrogen-ion concentration rise in active tissue", "A coronary artery becomes severely narrowed", "Excess tissue fluid enters blind-ended lymph capillaries", "Systemic arterial pressure remains chronically elevated" ], "answer": 2, "explanation": "The fluid and leaked proteins eventually return to the blood. Lymph vessels drain through larger ducts into veins near the heart." }, { "id": "circulation-lymph-return-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After excess tissue fluid enters blind-ended lymph capillaries, which explanation best links the change to its outcome?", "options": [ "Higher afterload opposes ejection and increases mechanical stress on endothelium", "Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right", "Reduced coronary flow limits aerobic respiration in the myocardium", "Lymph vessels drain through larger ducts into veins near the heart" ], "answer": 3, "explanation": "The fluid and leaked proteins eventually return to the blood. Lymph vessels drain through larger ducts into veins near the heart." }, { "id": "circulation-lymph-return-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: excess tissue fluid enters blind-ended lymph capillaries?", "options": [ "The fluid and leaked proteins eventually return to the blood — Lymph vessels drain through larger ducts into veins near the heart", "Haemoglobin releases oxygen more readily — Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right", "Part of the cardiac muscle receives less oxygen — Reduced coronary flow limits aerobic respiration in the myocardium", "The left ventricle works harder and vessel walls face greater damage — Higher afterload opposes ejection and increases mechanical stress on endothelium" ], "answer": 0, "explanation": "The fluid and leaked proteins eventually return to the blood. Lymph vessels drain through larger ducts into veins near the heart." }, { "id": "circulation-bohr-effect-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which immediate result is most consistent with this condition: Carbon dioxide and hydrogen-ion concentration rise in active tissue?", "options": [ "Part of the cardiac muscle receives less oxygen", "Haemoglobin releases oxygen more readily", "Venous return, stroke volume and arterial pressure fall", "The left ventricle works harder and vessel walls face greater damage" ], "answer": 1, "explanation": "Haemoglobin releases oxygen more readily. Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right." }, { "id": "circulation-bohr-effect-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which condition would most specifically produce this result: haemoglobin releases oxygen more readily?", "options": [ "Systemic arterial pressure remains chronically elevated", "A coronary artery becomes severely narrowed", "Carbon dioxide and hydrogen-ion concentration rise in active tissue", "A person rapidly loses a large volume of blood" ], "answer": 2, "explanation": "Haemoglobin releases oxygen more readily. Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right." }, { "id": "circulation-bohr-effect-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After carbon dioxide and hydrogen-ion concentration rise in active tissue, which explanation best links the change to its outcome?", "options": [ "Reduced coronary flow limits aerobic respiration in the myocardium", "Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship", "Higher afterload opposes ejection and increases mechanical stress on endothelium", "Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right" ], "answer": 3, "explanation": "Haemoglobin releases oxygen more readily. Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right." }, { "id": "circulation-bohr-effect-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: carbon dioxide and hydrogen-ion concentration rise in active tissue?", "options": [ "Haemoglobin releases oxygen more readily — Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right", "The left ventricle works harder and vessel walls face greater damage — Higher afterload opposes ejection and increases mechanical stress on endothelium", "Part of the cardiac muscle receives less oxygen — Reduced coronary flow limits aerobic respiration in the myocardium", "Venous return, stroke volume and arterial pressure fall — Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship" ], "answer": 0, "explanation": "Haemoglobin releases oxygen more readily. Lower pH reduces haemoglobin's oxygen affinity and shifts the dissociation curve right." }, { "id": "circulation-coronary-block-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "A coronary artery becomes severely narrowed. Which outcome follows most directly?", "options": [ "The left ventricle works harder and vessel walls face greater damage", "Part of the cardiac muscle receives less oxygen", "Venous return, stroke volume and arterial pressure fall", "Heart rate and contractility increase" ], "answer": 1, "explanation": "Part of the cardiac muscle receives less oxygen. Reduced coronary flow limits aerobic respiration in the myocardium." }, { "id": "circulation-coronary-block-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which change most directly explains this observation: part of the cardiac muscle receives less oxygen?", "options": [ "Systemic arterial pressure remains chronically elevated", "A person rapidly loses a large volume of blood", "A coronary artery becomes severely narrowed", "Sympathetic stimulation rises during exercise" ], "answer": 2, "explanation": "Part of the cardiac muscle receives less oxygen. Reduced coronary flow limits aerobic respiration in the myocardium." }, { "id": "circulation-coronary-block-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After a coronary artery becomes severely narrowed, which explanation best links the change to its outcome?", "options": [ "Higher afterload opposes ejection and increases mechanical stress on endothelium", "Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship", "Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "Reduced coronary flow limits aerobic respiration in the myocardium" ], "answer": 3, "explanation": "Part of the cardiac muscle receives less oxygen. Reduced coronary flow limits aerobic respiration in the myocardium." }, { "id": "circulation-coronary-block-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: a coronary artery becomes severely narrowed?", "options": [ "Part of the cardiac muscle receives less oxygen — Reduced coronary flow limits aerobic respiration in the myocardium", "Venous return, stroke volume and arterial pressure fall — Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship", "Heart rate and contractility increase — Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "The left ventricle works harder and vessel walls face greater damage — Higher afterload opposes ejection and increases mechanical stress on endothelium" ], "answer": 0, "explanation": "Part of the cardiac muscle receives less oxygen. Reduced coronary flow limits aerobic respiration in the myocardium." }, { "id": "circulation-hypertension-outcome", "chapter": "Circulation", "difficulty": "Standard", "stem": "After systemic arterial pressure remains chronically elevated, which observation is most likely?", "options": [ "Venous return, stroke volume and arterial pressure fall", "The left ventricle works harder and vessel walls face greater damage", "Heart rate and contractility increase", "It binds a higher proportion of oxygen" ], "answer": 1, "explanation": "The left ventricle works harder and vessel walls face greater damage. Higher afterload opposes ejection and increases mechanical stress on endothelium." }, { "id": "circulation-hypertension-cause", "chapter": "Circulation", "difficulty": "Standard", "stem": "A learner records that the left ventricle works harder and vessel walls face greater damage. Which preceding event best accounts for it?", "options": [ "A person rapidly loses a large volume of blood", "Sympathetic stimulation rises during exercise", "Systemic arterial pressure remains chronically elevated", "Fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin" ], "answer": 2, "explanation": "The left ventricle works harder and vessel walls face greater damage. Higher afterload opposes ejection and increases mechanical stress on endothelium." }, { "id": "circulation-hypertension-mechanism", "chapter": "Circulation", "difficulty": "Standard", "stem": "After systemic arterial pressure remains chronically elevated, which explanation best links the change to its outcome?", "options": [ "Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship", "Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood", "Higher afterload opposes ejection and increases mechanical stress on endothelium" ], "answer": 3, "explanation": "The left ventricle works harder and vessel walls face greater damage. Higher afterload opposes ejection and increases mechanical stress on endothelium." }, { "id": "circulation-hypertension-integrated", "chapter": "Circulation", "difficulty": "Standard", "stem": "Which paired outcome and explanation best follows from this condition: systemic arterial pressure remains chronically elevated?", "options": [ "The left ventricle works harder and vessel walls face greater damage — Higher afterload opposes ejection and increases mechanical stress on endothelium", "Venous return, stroke volume and arterial pressure fall — Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship", "Heart rate and contractility increase — Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "It binds a higher proportion of oxygen — Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood" ], "answer": 0, "explanation": "The left ventricle works harder and vessel walls face greater damage. Higher afterload opposes ejection and increases mechanical stress on endothelium." }, { "id": "circulation-haemorrhage-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "A student models this change: A person rapidly loses a large volume of blood. What should the model predict first?", "options": [ "Heart rate and contractility increase", "Venous return, stroke volume and arterial pressure fall", "It binds a higher proportion of oxygen", "Tissue oedema becomes more likely" ], "answer": 1, "explanation": "Venous return, stroke volume and arterial pressure fall. Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship." }, { "id": "circulation-haemorrhage-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "What is the most likely cause when venous return, stroke volume and arterial pressure fall?", "options": [ "Sympathetic stimulation rises during exercise", "Fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin", "A person rapidly loses a large volume of blood", "Plasma albumin concentration falls markedly" ], "answer": 2, "explanation": "Venous return, stroke volume and arterial pressure fall. Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship." }, { "id": "circulation-haemorrhage-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After a person rapidly loses a large volume of blood, which explanation best links the change to its outcome?", "options": [ "Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood", "Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship" ], "answer": 3, "explanation": "Venous return, stroke volume and arterial pressure fall. Reduced circulating volume lowers ventricular filling through the Frank-Starling relationship." }, { "id": "circulation-exercise-output-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: Sympathetic stimulation rises during exercise?", "options": [ "Heart rate and contractility increase", "Tissue oedema becomes more likely", "A thrombus may acutely stop blood flow and cause myocardial infarction", "It binds a higher proportion of oxygen" ], "answer": 0, "explanation": "Heart rate and contractility increase. Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling." }, { "id": "circulation-exercise-output-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: heart rate and contractility increase?", "options": [ "Fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin", "Sympathetic stimulation rises during exercise", "Plasma albumin concentration falls markedly", "An atherosclerotic plaque ruptures inside a coronary artery" ], "answer": 1, "explanation": "Heart rate and contractility increase. Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling." }, { "id": "circulation-exercise-output-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After sympathetic stimulation rises during exercise, which explanation best links the change to its outcome?", "options": [ "Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood", "Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling", "Exposed plaque material activates platelets and the clotting cascade" ], "answer": 2, "explanation": "Heart rate and contractility increase. Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling." }, { "id": "circulation-exercise-output-integrated", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: sympathetic stimulation rises during exercise?", "options": [ "It binds a higher proportion of oxygen — Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood", "Tissue oedema becomes more likely — Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "A thrombus may acutely stop blood flow and cause myocardial infarction — Exposed plaque material activates platelets and the clotting cascade", "Heart rate and contractility increase — Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling" ], "answer": 3, "explanation": "Heart rate and contractility increase. Noradrenaline acts on cardiac beta receptors to accelerate pacemaker activity and calcium cycling." }, { "id": "circulation-fetal-haemoglobin-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin. Which outcome follows most directly?", "options": [ "It binds a higher proportion of oxygen", "Tissue oedema becomes more likely", "A thrombus may acutely stop blood flow and cause myocardial infarction", "The ventricles depolarize less synchronously" ], "answer": 0, "explanation": "It binds a higher proportion of oxygen. Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood." }, { "id": "circulation-fetal-haemoglobin-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which change most directly explains this observation: it binds a higher proportion of oxygen?", "options": [ "Plasma albumin concentration falls markedly", "Fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin", "An atherosclerotic plaque ruptures inside a coronary artery", "Conduction through one ventricular bundle branch is blocked" ], "answer": 1, "explanation": "It binds a higher proportion of oxygen. Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood." }, { "id": "circulation-fetal-haemoglobin-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin, which explanation best links the change to its outcome?", "options": [ "Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "Exposed plaque material activates platelets and the clotting cascade", "Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood", "The affected region must receive excitation by slower cell-to-cell spread from the intact side" ], "answer": 2, "explanation": "It binds a higher proportion of oxygen. Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood." }, { "id": "circulation-fetal-haemoglobin-integrated", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: fetal haemoglobin is exposed to the same oxygen pressure as adult haemoglobin?", "options": [ "Tissue oedema becomes more likely — Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "A thrombus may acutely stop blood flow and cause myocardial infarction — Exposed plaque material activates platelets and the clotting cascade", "The ventricles depolarize less synchronously — The affected region must receive excitation by slower cell-to-cell spread from the intact side", "It binds a higher proportion of oxygen — Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood" ], "answer": 3, "explanation": "It binds a higher proportion of oxygen. Its greater oxygen affinity helps transfer oxygen from maternal to fetal blood." }, { "id": "circulation-low-albumin-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After plasma albumin concentration falls markedly, which observation is most likely?", "options": [ "Tissue oedema becomes more likely", "A thrombus may acutely stop blood flow and cause myocardial infarction", "The ventricles depolarize less synchronously", "It passes through the heart twice during one full journey" ], "answer": 0, "explanation": "Tissue oedema becomes more likely. Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid." }, { "id": "circulation-low-albumin-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "A learner records that tissue oedema becomes more likely. Which preceding event best accounts for it?", "options": [ "An atherosclerotic plaque ruptures inside a coronary artery", "Plasma albumin concentration falls markedly", "Conduction through one ventricular bundle branch is blocked", "Blood completes separate pulmonary and systemic circuits" ], "answer": 1, "explanation": "Tissue oedema becomes more likely. Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid." }, { "id": "circulation-low-albumin-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After plasma albumin concentration falls markedly, which explanation best links the change to its outcome?", "options": [ "Exposed plaque material activates platelets and the clotting cascade", "The affected region must receive excitation by slower cell-to-cell spread from the intact side", "Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid", "The right heart sends blood to lungs and the left heart sends it to the body" ], "answer": 2, "explanation": "Tissue oedema becomes more likely. Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid." }, { "id": "circulation-low-albumin-integrated", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: plasma albumin concentration falls markedly?", "options": [ "It passes through the heart twice during one full journey — The right heart sends blood to lungs and the left heart sends it to the body", "A thrombus may acutely stop blood flow and cause myocardial infarction — Exposed plaque material activates platelets and the clotting cascade", "The ventricles depolarize less synchronously — The affected region must receive excitation by slower cell-to-cell spread from the intact side", "Tissue oedema becomes more likely — Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid" ], "answer": 3, "explanation": "Tissue oedema becomes more likely. Reduced plasma oncotic pressure decreases capillary reabsorption of filtered fluid." }, { "id": "circulation-atheroma-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "A student models this change: An atherosclerotic plaque ruptures inside a coronary artery. What should the model predict first?", "options": [ "A thrombus may acutely stop blood flow and cause myocardial infarction", "It passes through the heart twice during one full journey", "The ventricles depolarize less synchronously", "Its thick elastic wall stretches and recoils" ], "answer": 0, "explanation": "A thrombus may acutely stop blood flow and cause myocardial infarction. Exposed plaque material activates platelets and the clotting cascade." }, { "id": "circulation-atheroma-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "What is the most likely cause when a thrombus may acutely stop blood flow and cause myocardial infarction?", "options": [ "Conduction through one ventricular bundle branch is blocked", "An atherosclerotic plaque ruptures inside a coronary artery", "An artery receives high-pressure blood from a ventricle", "Blood completes separate pulmonary and systemic circuits" ], "answer": 1, "explanation": "A thrombus may acutely stop blood flow and cause myocardial infarction. Exposed plaque material activates platelets and the clotting cascade." }, { "id": "circulation-atheroma-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After an atherosclerotic plaque ruptures inside a coronary artery, which explanation best links the change to its outcome?", "options": [ "The right heart sends blood to lungs and the left heart sends it to the body", "The affected region must receive excitation by slower cell-to-cell spread from the intact side", "Exposed plaque material activates platelets and the clotting cascade", "Elastic tissue smooths pressure changes while muscle and collagen resist rupture" ], "answer": 2, "explanation": "A thrombus may acutely stop blood flow and cause myocardial infarction. Exposed plaque material activates platelets and the clotting cascade." }, { "id": "circulation-atheroma-integrated", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: an atherosclerotic plaque ruptures inside a coronary artery?", "options": [ "The ventricles depolarize less synchronously — The affected region must receive excitation by slower cell-to-cell spread from the intact side", "Its thick elastic wall stretches and recoils — Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "It passes through the heart twice during one full journey — The right heart sends blood to lungs and the left heart sends it to the body", "A thrombus may acutely stop blood flow and cause myocardial infarction — Exposed plaque material activates platelets and the clotting cascade" ], "answer": 3, "explanation": "A thrombus may acutely stop blood flow and cause myocardial infarction. Exposed plaque material activates platelets and the clotting cascade." }, { "id": "circulation-bundle-block-outcome", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which immediate result is most consistent with this condition: Conduction through one ventricular bundle branch is blocked?", "options": [ "The ventricles depolarize less synchronously", "Its thick elastic wall stretches and recoils", "Backflow is limited when blood pressure is low", "It passes through the heart twice during one full journey" ], "answer": 0, "explanation": "The ventricles depolarize less synchronously. The affected region must receive excitation by slower cell-to-cell spread from the intact side." }, { "id": "circulation-bundle-block-cause", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which condition would most specifically produce this result: the ventricles depolarize less synchronously?", "options": [ "Blood completes separate pulmonary and systemic circuits", "Conduction through one ventricular bundle branch is blocked", "An artery receives high-pressure blood from a ventricle", "A limb vein contains one-way valves" ], "answer": 1, "explanation": "The ventricles depolarize less synchronously. The affected region must receive excitation by slower cell-to-cell spread from the intact side." }, { "id": "circulation-bundle-block-mechanism", "chapter": "Circulation", "difficulty": "Challenge", "stem": "After conduction through one ventricular bundle branch is blocked, which explanation best links the change to its outcome?", "options": [ "The right heart sends blood to lungs and the left heart sends it to the body", "Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "The affected region must receive excitation by slower cell-to-cell spread from the intact side", "Valve cusps close if blood begins moving away from the heart" ], "answer": 2, "explanation": "The ventricles depolarize less synchronously. The affected region must receive excitation by slower cell-to-cell spread from the intact side." }, { "id": "circulation-bundle-block-integrated", "chapter": "Circulation", "difficulty": "Challenge", "stem": "Which paired outcome and explanation best follows from this condition: conduction through one ventricular bundle branch is blocked?", "options": [ "It passes through the heart twice during one full journey — The right heart sends blood to lungs and the left heart sends it to the body", "Its thick elastic wall stretches and recoils — Elastic tissue smooths pressure changes while muscle and collagen resist rupture", "Backflow is limited when blood pressure is low — Valve cusps close if blood begins moving away from the heart", "The ventricles depolarize less synchronously — The affected region must receive excitation by slower cell-to-cell spread from the intact side" ], "answer": 3, "explanation": "The ventricles depolarize less synchronously. The affected region must receive excitation by slower cell-to-cell spread from the intact side." }, { "chapter": "Circulation", "id": "applied-cardiac-output", "difficulty": "Standard", "stem": "A heart beats 75 times per minute with a stroke volume of 80 mL. What is its cardiac output?", "options": [ "6 L min⁻¹", "0.6 L min⁻¹", "60 L min⁻¹", "155 mL min⁻¹" ], "answer": 0, "explanation": "Cardiac output = heart rate × stroke volume = 75 × 80 = 6,000 mL min⁻¹, or 6 L min⁻¹." }, { "chapter": "Circulation", "id": "applied-valve-pressure", "difficulty": "Challenge", "stem": "At one instant, left ventricular pressure is greater than left atrial pressure but lower than aortic pressure. Which valve state is expected?", "options": [ "Mitral open; aortic open", "Mitral closed; aortic closed", "Mitral open; aortic closed", "Mitral closed; aortic open" ], "answer": 1, "explanation": "Ventricular pressure above atrial pressure closes the mitral valve. Aortic pressure above ventricular pressure keeps the aortic valve closed. Both can be closed during isovolumetric phases." }, { "chapter": "Circulation", "id": "applied-pulmonary-route", "difficulty": "Foundation", "stem": "Which chamber is X in this route?", "options": [ "Right atrium", "Left ventricle", "Left atrium", "Right ventricle" ], "answer": 2, "explanation": "Oxygenated blood returning from the lungs enters the left atrium through pulmonary veins, then passes to the left ventricle.", "visual": { "kind": "flow", "caption": "Blood returning from gas exchange", "nodes": [ "Lung capillaries", "Pulmonary veins", "X", "Left ventricle" ] } }, { "chapter": "Circulation", "id": "applied-capillary-velocity", "difficulty": "Standard", "stem": "Why is mean blood speed relatively low across the systemic capillary network?", "options": [ "All blood pressure disappears at the arterial end", "Each capillary has its own beating heart", "Capillary blood contains no water", "The network has a very large combined cross-sectional area" ], "answer": 3, "explanation": "For a given volume flow, a larger total cross-sectional area corresponds to lower mean velocity. The many parallel capillaries create this large combined area." } ] }