Cardiac cycle MCQs With Answer

Introduction:

The “Cardiac cycle MCQs With Answer” resource is designed for B. Pharm students seeking a focused review of cardiac physiology and pharmacological implications. This concise, Student-friendly guide covers key concepts like Wigger’s diagram, isovolumetric phases, valve mechanics, heart sounds, stroke volume, ejection fraction, preload, afterload, and autonomic modulation. Each MCQ emphasizes clinical relevance and drug effects on the cycle to strengthen exam readiness and practical understanding. Clear explanations and targeted questions help consolidate knowledge essential for cardiovascular pharmacology and therapeutics. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary event that begins ventricular systole in the cardiac cycle?

• Opening of the aortic valve
• Depolarization of the atria
• Closure of the atrioventricular (AV) valves
• Onset of ventricular repolarization

Correct Answer: Closure of the atrioventricular (AV) valves

Q2. During isovolumetric contraction, which of the following is true?

• Ventricular volume increases while pressure falls
• Both inlet and outlet valves are closed
• Aortic valve is open and mitral valve is open
• Blood is ejected into the pulmonary artery

Correct Answer: Both inlet and outlet valves are closed

Q3. Which heart sound corresponds to closure of the mitral and tricuspid valves?

• S2
• S3
• S1
• Splitting of S2

Correct Answer: S1

Q4. The dicrotic notch on the aortic pressure curve reflects which event?

• Opening of the mitral valve
• Closure of the aortic valve
• Isovolumetric contraction
• Onset of atrial contraction

Correct Answer: Closure of the aortic valve

Q5. Which phase of the cardiac cycle follows ventricular ejection?

• Isovolumetric relaxation
• Atrial systole
• Passive ventricular filling
• Isovolumetric contraction

Correct Answer: Isovolumetric relaxation

Q6. Normal ejection fraction in a healthy adult is approximately:

• 20–30%
• 35–45%
• 55–70%
• 80–95%

Correct Answer: 55–70%

Q7. Which parameter represents preload most directly?

• Systemic vascular resistance
• Left ventricular end-diastolic volume (LVEDV)
• Heart rate
• Mean arterial pressure

Correct Answer: Left ventricular end-diastolic volume (LVEDV)

Q8. According to the Frank-Starling law, increasing venous return results in:

• Decreased stroke volume
• Unchanged cardiac output
• Increased stroke volume up to a physiological limit
• Immediate decrease in contractility

Correct Answer: Increased stroke volume up to a physiological limit

Q9. Which interval in the cardiac cycle shortens most with increased heart rate?

• Duration of isovolumetric contraction
• Diastolic filling time
• Duration of ventricular ejection
• Time of atrial systole

Correct Answer: Diastolic filling time

Q10. S2 splitting during inspiration is due to delayed closure of which valve?

• Mitral valve
• Aortic valve
• Pulmonary valve
• Tricuspid valve

Correct Answer: Pulmonary valve

Q11. Which drug class increases contractility (positive inotropy) by increasing intracellular Ca2+ availability?

• Beta-blockers
• Calcium channel blockers (non-dihydropyridine)
• Cardiac glycosides (digoxin)
• ACE inhibitors

Correct Answer: Cardiac glycosides (digoxin)

Q12. The end-systolic volume (ESV) is most influenced by which factor?

• Preload only
• Afterload and contractility
• Heart valve area only
• Atrial size only

Correct Answer: Afterload and contractility

Q13. Which component of the ECG corresponds approximately to ventricular repolarization?

• PR interval
• QRS complex
• T wave
• P wave

Correct Answer: T wave

Q14. During passive ventricular filling, which valve is open?

• Aortic valve
• Pulmonary valve
• Mitral valve
• Tricuspid valve is closed

Correct Answer: Mitral valve

Q15. Which term best describes the pressure the ventricle must overcome to eject blood?

• Preload
• Afterload
• Compliance
• Contractility

Correct Answer: Afterload

Q16. A systolic murmur heard best at the left lower sternal border likely suggests pathology of which valve?

• Aortic valve
• Pulmonary valve
• Mitral valve
• Tricuspid valve

Correct Answer: Tricuspid valve

Q17. Which event increases left ventricular pressure but does not change volume?

• Ventricular ejection
• Isovolumetric contraction
• Passive ventricular filling
• Atrial contraction

Correct Answer: Isovolumetric contraction

Q18. Mean arterial pressure (MAP) is best estimated by which formula?

• Systolic BP + Diastolic BP divided by 2
• Diastolic BP + 1/3 (Systolic BP − Diastolic BP)
• Heart rate × Stroke volume
• Systolic BP − Diastolic BP

Correct Answer: Diastolic BP + 1/3 (Systolic BP − Diastolic BP)

Q19. Which physiological change reduces end-diastolic volume?

• Increased venous return
• Increased heart rate with shortened filling time
• Enhanced atrial contraction
• Peripheral vasodilation increasing venous pooling

Correct Answer: Increased heart rate with shortened filling time

Q20. The pressure-volume loop area represents which cardiac parameter?

• Stroke volume
• Cardiac output
• Work done by the ventricle (stroke work)
• Ejection fraction

Correct Answer: Work done by the ventricle (stroke work)

Q21. Which valve lesion commonly causes a holosystolic murmur radiating to the axilla?

• Aortic stenosis
• Mitral regurgitation
• Tricuspid stenosis
• Pulmonic regurgitation

Correct Answer: Mitral regurgitation

Q22. Which autonomic effect increases heart rate via sinoatrial node stimulation?

• Vagal stimulation (parasympathetic)
• Sympathetic stimulation (beta-1 adrenergic)
• Increased baroreceptor firing
• Activation of atrial stretch receptors decreasing firing

Correct Answer: Sympathetic stimulation (beta-1 adrenergic)

Q23. Which measurement decreases when afterload increases, assuming contractility is constant?

• End-diastolic volume
• End-systolic volume
• Stroke volume
• Heart rate

Correct Answer: Stroke volume

Q24. The first heart sound (S1) marks the beginning of which mechanical event?

• Ventricular diastole
• Ventricular systole
• Atrial diastole
• Isovolumetric relaxation

Correct Answer: Ventricular systole

Q25. A prominent S3 gallop in adults often indicates which condition?

• Normal young healthy heart
• Decreased ventricular filling pressures
• Ventricular volume overload or systolic dysfunction
• Right atrial enlargement

Correct Answer: Ventricular volume overload or systolic dysfunction

Q26. Which ion movement primarily causes ventricular muscle cell repolarization?

• Influx of Ca2+
• Efflux of K+
• Influx of Na+
• Influx of Cl−

Correct Answer: Efflux of K+

Q27. Which of the following best describes preload for the left ventricle?

• Wall stress during ejection
• Stretch of ventricular fibers at end-diastole
• Vascular resistance opposing ejection
• Rate of pressure rise during contraction

Correct Answer: Stretch of ventricular fibers at end-diastole

Q28. Which pharmacologic agent decreases heart rate and prolongs diastolic filling time?

• Isoproterenol
• Atropine
• Beta-blockers (e.g., metoprolol)
• Dobutamine

Correct Answer: Beta-blockers (e.g., metoprolol)

Q29. Which statement about ventricular ejection is correct?

• Ejection begins when ventricular pressure falls below atrial pressure
• Ejection ends with closure of the AV valves
• Ejection occurs when ventricular pressure exceeds arterial pressure
• Ejection volume equals end-diastolic volume

Correct Answer: Ejection occurs when ventricular pressure exceeds arterial pressure

Q30. The PR interval on ECG reflects the time for which process?

• Ventricular depolarization
• Atrial depolarization and AV nodal delay
• Ventricular repolarization
• SA node automaticity only

Correct Answer: Atrial depolarization and AV nodal delay

Q31. In left ventricular pressure-volume loop, an upward and leftward shift indicates:

• Decreased contractility
• Increased afterload
• Increased contractility
• Increased preload only

Correct Answer: Increased contractility

Q32. Which condition prolongs isovolumetric relaxation phase?

• Enhanced ventricular relaxation
• Increased left ventricular end-systolic pressure
• Rapid fall in arterial pressure
• Decreased afterload

Correct Answer: Increased left ventricular end-systolic pressure

Q33. Which physiologic change will most increase cardiac output acutely?

• Decrease in heart rate with fixed stroke volume
• Significant increase in systemic vascular resistance
• Acute increase in venous return boosting stroke volume
• Acute severe mitral regurgitation

Correct Answer: Acute increase in venous return boosting stroke volume

Q34. Which finding is typical of aortic stenosis during the cardiac cycle?

• Soft S1 and wide-split S2
• Systolic ejection murmur with slow rising pulse
• Diastolic decrescendo murmur
• Pansystolic murmur loudest at apex

Correct Answer: Systolic ejection murmur with slow rising pulse

Q35. Which parameter is directly decreased by a positive afterload effect?

• End-diastolic volume
• Stroke volume
• Preload
• Heart rate

Correct Answer: Stroke volume

Q36. The S2 heart sound consists mainly of closure sounds from which two valves?

• Mitral and tricuspid
• Aortic and pulmonary
• Mitral and aortic
• Tricuspid and pulmonary

Correct Answer: Aortic and pulmonary

Q37. During which phase does atrial contraction contribute most to ventricular filling?

• Late diastole
• Early systole
• Isovolumetric relaxation
• Mid systole

Correct Answer: Late diastole

Q38. Which alteration would most likely reduce stroke volume?

• Decreased systemic vascular resistance
• Increased contractility from sympathetic activity
• Severe mitral regurgitation causing volume loss into atrium
• Augmented preload from fluid administration

Correct Answer: Severe mitral regurgitation causing volume loss into atrium

Q39. Which measure increases when sympathetic tone increases myocardial contractility?

• End-systolic volume
• End-diastolic volume
• Stroke volume
• Peripheral venous compliance

Correct Answer: Stroke volume

Q40. A diastolic murmur best heard at the left sternal border suggests which lesion?

• Aortic regurgitation
• Mitral regurgitation
• Aortic stenosis
• Tricuspid regurgitation

Correct Answer: Aortic regurgitation

Q41. What is the main effect of ACE inhibitors relevant to afterload?

• Increase systemic vascular resistance
• Decrease systemic vascular resistance and afterload
• Increase heart rate directly
• Increase preload by fluid retention

Correct Answer: Decrease systemic vascular resistance and afterload

Q42. Which change is characteristic of heart failure with reduced ejection fraction?

• Increased ejection fraction
• Normal stroke volume with low preload
• Decreased contractility with increased end-systolic volume
• Enhanced ventricular compliance only

Correct Answer: Decreased contractility with increased end-systolic volume

Q43. Which factor predominantly determines the intensity of S1?

• Closure of semilunar valves
• Forceful closure of AV valves due to increased ventricular pressure
• Opening of AV valves
• Pulmonary arterial pressure

Correct Answer: Forceful closure of AV valves due to increased ventricular pressure

Q44. Which phase of the cardiac cycle is most prolonged at rest in healthy adults?

• Systole
• Diastole
• Isovolumetric contraction only
• Atrial systole only

Correct Answer: Diastole

Q45. Which mechanism explains why increased afterload reduces stroke volume?

• Increased afterload shortens diastole and reduces filling time
• Higher arterial pressure opposes ventricular ejection increasing end-systolic volume
• It decreases venous return directly
• It increases heart rate causing reduced stroke volume

Correct Answer: Higher arterial pressure opposes ventricular ejection increasing end-systolic volume

Q46. Which of the following best describes the effect of calcium channel blockers (verapamil) on the cardiac cycle?

• Increase myocardial contractility and shorten systole
• Decrease conduction through AV node and reduce contractility
• Increase heart rate via sinoatrial stimulation
• Primarily increase preload

Correct Answer: Decrease conduction through AV node and reduce contractility

Q47. Which pressure is highest during diastole in the left ventricle?

• Peak systolic pressure
• End-diastolic pressure
• Isovolumetric contraction pressure
• Atrial systolic pressure

Correct Answer: End-diastolic pressure

Q48. Which clinical measurement is directly calculated as stroke volume × heart rate?

• Mean arterial pressure
• Cardiac output
• Ejection fraction
• Systemic vascular resistance

Correct Answer: Cardiac output

Q49. Which abnormality shortens the time between S1 and S2 and may indicate tachycardia?

• Prolonged diastole
• Shortened systolic ejection time due to decreased stroke volume
• Increased heart rate reducing systolic and diastolic durations
• First-degree AV block

Correct Answer: Increased heart rate reducing systolic and diastolic durations

Q50. Which physiological change increases right ventricular ejection fraction relative to left ventricle under normal conditions?

• Higher pulmonary vascular resistance compared to systemic
• Lower afterload in the pulmonary circulation
• Greater wall thickness of right ventricle
• Higher oxygen demand in the right ventricle

Correct Answer: Lower afterload in the pulmonary circulation

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com