COMSAE PHASE 1 CARDIOVASCULAR
PHYSIOLOGY PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A 24-year-old medical student has a resting heart rate of 70/min
and a stroke volume of 70 mL. During moderate exercise, his heart
rate increases to 140/min and his stroke volume increases to 100
mL. Which of the following is the approximate change in cardiac
output?
A. It decreases from 4.9 L/min to 4.2 L/min
B. It increases from 4.9 L/min to 7.0 L/min
C. It increases from 4.9 L/min to 14.0 L/min
D. It increases from 7.0 L/min to 14.0 L/min
E. It remains unchanged at approximately 7.0 L/min
Answer: C. It increases from 4.9 L/min to 14.0 L/min
Rationale: Cardiac output (CO) = heart rate × stroke volume. At rest,
CO = 70 × 70 = 4,900 mL/min, or 4.9 L/min. During exercise, CO =
140 × 100 = 14,000 mL/min, or 14 L/min. The large increase results
from both tachycardia and increased stroke volume.
2. A patient with acute hemorrhage loses approximately 20% of his
circulating blood volume. His arterial pressure begins to fall.
Which immediate cardiovascular response is most likely mediated
by the arterial baroreceptor reflex?
1
,A. Increased vagal activity and decreased sympathetic activity
B. Increased sympathetic activity causing tachycardia and peripheral
vasoconstriction
C. Decreased renin secretion
D. Decreased myocardial contractility
E. Arteriolar dilation in skeletal muscle
Answer: B. Increased sympathetic activity causing tachycardia and
peripheral vasoconstriction
Rationale: A decrease in arterial pressure decreases stretch of the
carotid sinus and aortic arch baroreceptors. Their firing rate
decreases, reducing inhibitory input to the medullary cardiovascular
centers. Sympathetic activity increases while parasympathetic activity
decreases, producing tachycardia, increased contractility,
venoconstriction, and arteriolar vasoconstriction.
3. Which property of cardiac muscle is primarily responsible for
preventing sustained tetanic contraction of the ventricles?
A. Low extracellular calcium concentration
B. A prolonged absolute refractory period
C. Rapid sodium-channel recovery
D. Lack of voltage-gated calcium channels
E. Hyperpolarization during phase 2
Answer: B. A prolonged absolute refractory period
Rationale: Cardiac ventricular myocytes have a prolonged action
potential and absolute refractory period caused largely by the plateau
phase. Because the refractory period overlaps most of mechanical
contraction, a second action potential cannot summate with the first to
produce tetanus. This is essential because continuous cardiac
contraction would prevent effective ventricular filling and pumping.
2
, 4. A patient develops increased sympathetic stimulation of the heart.
Which combination of changes is expected?
A. Decreased heart rate, decreased contractility, decreased conduction
velocity
B. Increased heart rate, increased contractility, increased AV nodal
conduction
C. Increased heart rate, decreased contractility, increased vagal tone
D. Decreased heart rate, increased contractility, decreased conduction
velocity
E. No change in cardiac function because sympathetic effects are
restricted to blood vessels
Answer: B. Increased heart rate, increased contractility, increased
AV nodal conduction
Rationale: Sympathetic stimulation activates β1-adrenergic receptors
in the sinoatrial node, atrioventricular node, and ventricular
myocardium. Increased cAMP enhances pacemaker activity, increases
heart rate, accelerates AV conduction, and increases myocardial
contractility.
5. A 68-year-old man with hypertension develops left ventricular
hypertrophy. Which cellular adaptation directly allows the
ventricle to generate greater wall tension against increased
afterload?
A. Increased sarcomere number in series
B. Increased sarcomere number in parallel
C. Reduced myocyte protein synthesis
D. Decreased ventricular wall thickness
E. Increased ventricular compliance
3
, Answer: B. Increased sarcomere number in parallel
Rationale: Chronic pressure overload produces concentric
hypertrophy. Cardiomyocytes add sarcomeres in parallel, increasing
wall thickness and allowing the ventricle to generate greater pressure.
By contrast, chronic volume overload generally produces eccentric
hypertrophy with sarcomeres added in series.
6. A patient has an end-diastolic volume of 150 mL and an end-
systolic volume of 60 mL. What is his ejection fraction?
A. 30%
B. 40%
C. 50%
D. 60%
E. 90%
Answer: D. 60%
Rationale: Stroke volume = EDV − ESV = 150 − 60 = 90 mL. Ejection
fraction = SV/EDV × 100 = 90/150 × 100 = 60%. Ejection fraction
represents the fraction of ventricular end-diastolic blood volume
ejected during systole.
7. Which phase of the ventricular action potential is primarily
responsible for the plateau phase?
A. Rapid sodium influx
B. Transient potassium efflux
C. Calcium influx through L-type calcium channels balanced by
potassium efflux
D. Sodium-potassium pump activation
E. Chloride influx
4
PHYSIOLOGY PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A 24-year-old medical student has a resting heart rate of 70/min
and a stroke volume of 70 mL. During moderate exercise, his heart
rate increases to 140/min and his stroke volume increases to 100
mL. Which of the following is the approximate change in cardiac
output?
A. It decreases from 4.9 L/min to 4.2 L/min
B. It increases from 4.9 L/min to 7.0 L/min
C. It increases from 4.9 L/min to 14.0 L/min
D. It increases from 7.0 L/min to 14.0 L/min
E. It remains unchanged at approximately 7.0 L/min
Answer: C. It increases from 4.9 L/min to 14.0 L/min
Rationale: Cardiac output (CO) = heart rate × stroke volume. At rest,
CO = 70 × 70 = 4,900 mL/min, or 4.9 L/min. During exercise, CO =
140 × 100 = 14,000 mL/min, or 14 L/min. The large increase results
from both tachycardia and increased stroke volume.
2. A patient with acute hemorrhage loses approximately 20% of his
circulating blood volume. His arterial pressure begins to fall.
Which immediate cardiovascular response is most likely mediated
by the arterial baroreceptor reflex?
1
,A. Increased vagal activity and decreased sympathetic activity
B. Increased sympathetic activity causing tachycardia and peripheral
vasoconstriction
C. Decreased renin secretion
D. Decreased myocardial contractility
E. Arteriolar dilation in skeletal muscle
Answer: B. Increased sympathetic activity causing tachycardia and
peripheral vasoconstriction
Rationale: A decrease in arterial pressure decreases stretch of the
carotid sinus and aortic arch baroreceptors. Their firing rate
decreases, reducing inhibitory input to the medullary cardiovascular
centers. Sympathetic activity increases while parasympathetic activity
decreases, producing tachycardia, increased contractility,
venoconstriction, and arteriolar vasoconstriction.
3. Which property of cardiac muscle is primarily responsible for
preventing sustained tetanic contraction of the ventricles?
A. Low extracellular calcium concentration
B. A prolonged absolute refractory period
C. Rapid sodium-channel recovery
D. Lack of voltage-gated calcium channels
E. Hyperpolarization during phase 2
Answer: B. A prolonged absolute refractory period
Rationale: Cardiac ventricular myocytes have a prolonged action
potential and absolute refractory period caused largely by the plateau
phase. Because the refractory period overlaps most of mechanical
contraction, a second action potential cannot summate with the first to
produce tetanus. This is essential because continuous cardiac
contraction would prevent effective ventricular filling and pumping.
2
, 4. A patient develops increased sympathetic stimulation of the heart.
Which combination of changes is expected?
A. Decreased heart rate, decreased contractility, decreased conduction
velocity
B. Increased heart rate, increased contractility, increased AV nodal
conduction
C. Increased heart rate, decreased contractility, increased vagal tone
D. Decreased heart rate, increased contractility, decreased conduction
velocity
E. No change in cardiac function because sympathetic effects are
restricted to blood vessels
Answer: B. Increased heart rate, increased contractility, increased
AV nodal conduction
Rationale: Sympathetic stimulation activates β1-adrenergic receptors
in the sinoatrial node, atrioventricular node, and ventricular
myocardium. Increased cAMP enhances pacemaker activity, increases
heart rate, accelerates AV conduction, and increases myocardial
contractility.
5. A 68-year-old man with hypertension develops left ventricular
hypertrophy. Which cellular adaptation directly allows the
ventricle to generate greater wall tension against increased
afterload?
A. Increased sarcomere number in series
B. Increased sarcomere number in parallel
C. Reduced myocyte protein synthesis
D. Decreased ventricular wall thickness
E. Increased ventricular compliance
3
, Answer: B. Increased sarcomere number in parallel
Rationale: Chronic pressure overload produces concentric
hypertrophy. Cardiomyocytes add sarcomeres in parallel, increasing
wall thickness and allowing the ventricle to generate greater pressure.
By contrast, chronic volume overload generally produces eccentric
hypertrophy with sarcomeres added in series.
6. A patient has an end-diastolic volume of 150 mL and an end-
systolic volume of 60 mL. What is his ejection fraction?
A. 30%
B. 40%
C. 50%
D. 60%
E. 90%
Answer: D. 60%
Rationale: Stroke volume = EDV − ESV = 150 − 60 = 90 mL. Ejection
fraction = SV/EDV × 100 = 90/150 × 100 = 60%. Ejection fraction
represents the fraction of ventricular end-diastolic blood volume
ejected during systole.
7. Which phase of the ventricular action potential is primarily
responsible for the plateau phase?
A. Rapid sodium influx
B. Transient potassium efflux
C. Calcium influx through L-type calcium channels balanced by
potassium efflux
D. Sodium-potassium pump activation
E. Chloride influx
4
