ACSM-EP Cardiovascular Physiology 3 — Questions and Answers
Question 1: Which vessel type has the greatest cross-sectional area and the slowest blood velocity?
- Aorta
- Arterioles
- Capillaries (Correct answer)
- Venules
Correct answer: Capillaries
Capillaries collectively have the greatest total cross-sectional area, which by continuity of flow results in the slowest blood velocity, facilitating gas and nutrient exchange.
Question 2: In the context of exercise physiology, which statement about the arteriovenous oxygen difference (a-vO₂ diff) is correct?
- It decreases at maximal exercise intensity
- It remains constant regardless of exercise intensity
- It widens progressively with increasing exercise intensity (Correct answer)
- It only reflects pulmonary oxygen uptake
Correct answer: It widens progressively with increasing exercise intensity
The a-vO₂ difference widens as exercise intensity increases because working muscles extract more oxygen from arterial blood, lowering mixed venous PO₂.
Question 3: Which component of blood pressure regulation is primarily controlled by the kidneys?
- Acute heart rate changes
- Long-term blood volume via renin-angiotensin-aldosterone system (Correct answer)
- Immediate baroreceptor reflex
- Sympathetic vasoconstriction during exercise
Correct answer: Long-term blood volume via renin-angiotensin-aldosterone system
The kidneys regulate long-term blood pressure through the renin-angiotensin-aldosterone system, which controls sodium retention and blood volume.
Question 4: What is the approximate ejection fraction at rest in a healthy individual?
- 30–40%
- 50–70% (Correct answer)
- 75–85%
- 90–100%
Correct answer: 50–70%
Normal resting ejection fraction is approximately 55–70%, reflecting the proportion of end-diastolic volume ejected with each heartbeat.
Question 5: Which ion is primarily responsible for the rapid depolarization phase (Phase 0) of the cardiac action potential in ventricular myocytes?
- Potassium (K⁺) efflux
- Calcium (Ca²⁺) influx
- Sodium (Na⁺) influx through fast channels (Correct answer)
- Chloride (Cl⁻) influx
Correct answer: Sodium (Na⁺) influx through fast channels
Phase 0 depolarization in ventricular cardiomyocytes is caused by rapid Na⁺ influx through voltage-gated fast sodium channels.
Question 6: During submaximal steady-state exercise, what happens to total peripheral resistance (TPR)?
- TPR increases proportionally with workload
- TPR decreases due to vasodilation in active muscle beds (Correct answer)
- TPR remains unchanged because cardiac output is constant
- TPR increases due to sympathetic activation in all vascular beds
Correct answer: TPR decreases due to vasodilation in active muscle beds
TPR decreases during submaximal exercise because vasodilation in active skeletal muscle exceeds sympathetic vasoconstriction in non-active beds.
Question 7: Which term describes the ventricular pressure that must be overcome for the heart to eject blood?
- Preload
- Contractility
- Afterload (Correct answer)
- Compliance
Correct answer: Afterload
Afterload is the resistance the ventricle must overcome to eject blood, largely determined by systemic vascular resistance and aortic pressure.
ACSM-EP Cardiovascular Physiology 3
Which vessel type has the greatest cross-sectional area and the slowest blood velocity?