Part 5: Human Heart – Anatomy, Valves, Cardiac Cycle, Heart Sounds (25 MCQs)

Part 5: Human Heart – Anatomy, Valves, Cardiac Cycle, Heart Sounds (25 MCQs)

Q1. The human heart is located in the:

A. Abdominal cavity
B. Thoracic cavity
C. Cranial cavity
D. Pelvic cavity

Answer: B

Explanation:

• A. Incorrect: Stomach, intestines are in abdominal cavity.
• B. Correct: Heart lies in thoracic cavity, between lungs.
• C. Incorrect: Brain in cranial cavity.
• D. Incorrect: Pelvic cavity houses urinary/reproductive organs.

Q2. The human heart is covered by a double-layered membrane called:

A. Pleura
B. Pericardium
C. Peritoneum
D. Endocardium

Answer: B

Explanation:

• A. Incorrect: Pleura covers lungs.
• B. Correct: Pericardium covers heart and contains pericardial fluid.
• C. Incorrect: Peritoneum covers abdominal organs.
• D. Incorrect: Endocardium is inner heart lining.

Q3. How many chambers are present in the human heart?

A. 2
B. 3
C. 4
D. 5

Answer: C

Explanation:

• A. Incorrect: 2 chambers in fish.
• B. Incorrect: 3 chambers in amphibians.
• C. Correct: Human heart has 4 chambers (2 atria, 2 ventricles).
• D. Incorrect: Not 5.

Q4. Which chamber of the heart has the thickest wall?

A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle

Answer: D

Explanation:

• A. Incorrect: Right atrium wall is thin.
• B. Incorrect: Right ventricle thinner than left.
• C. Incorrect: Left atrium also thin.
• D. Correct: Left ventricle pumps blood to whole body → thick wall.

Q5. Which valve prevents backflow from left ventricle to left atrium?

A. Tricuspid valve
B. Bicuspid (mitral) valve
C. Semilunar valve
D. Pulmonary valve

Answer: B

Explanation:

• A. Incorrect: Tricuspid valve is between RA and RV.
• B. Correct: Bicuspid/mitral valve between LA and LV prevents backflow.
• C. Incorrect: Semilunar valves prevent backflow into ventricles from arteries.
• D. Incorrect: Pulmonary valve between RV and pulmonary artery.

Q6. Tricuspid valve is present between:

A. Left atrium and left ventricle
B. Right atrium and right ventricle
C. Right ventricle and pulmonary artery
D. Left ventricle and aorta

Answer: B

Explanation:

• A. Incorrect: That’s bicuspid.
• B. Correct: Tricuspid valve → RA → RV.
• C. Incorrect: Pulmonary valve, not tricuspid.
• D. Incorrect: Aortic valve, not tricuspid.

Q7. Which blood vessel brings oxygenated blood from lungs to left atrium?

A. Pulmonary artery
B. Pulmonary vein
C. Vena cava
D. Aorta

Answer: B

Explanation:

• A. Incorrect: Pulmonary artery carries deoxygenated blood.
• B. Correct: Pulmonary vein carries oxygenated blood from lungs.
• C. Incorrect: Vena cava brings deoxygenated blood.
• D. Incorrect: Aorta carries blood away from heart.

Q8. Which blood vessel carries deoxygenated blood from right ventricle to lungs?

A. Pulmonary artery
B. Pulmonary vein
C. Aorta
D. Coronary artery

Answer: A

Explanation:

• A. Correct: Pulmonary artery carries deoxygenated blood to lungs.
• B. Incorrect: Pulmonary vein carries oxygenated blood.
• C. Incorrect: Aorta distributes oxygenated blood.
• D. Incorrect: Coronary artery supplies myocardium.

Q9. Which blood vessel carries deoxygenated blood from the body to right atrium?

A. Aorta
B. Pulmonary vein
C. Vena cava
D. Coronary sinus

Answer: C

Explanation:

• A. Incorrect: Aorta carries oxygenated blood out.
• B. Incorrect: Pulmonary vein carries oxygenated blood.
• C. Correct: Superior + inferior vena cava bring deoxygenated blood to RA.
• D. Incorrect: Coronary sinus drains only heart muscle.

Q10. Which valve prevents backflow from aorta to left ventricle?

A. Mitral valve
B. Tricuspid valve
C. Aortic semilunar valve
D. Pulmonary valve

Answer: C

Explanation:

• A. Incorrect: Mitral valve between LA and LV.
• B. Incorrect: Tricuspid valve between RA and RV.
• C. Correct: Aortic semilunar valve prevents backflow from aorta.
• D. Incorrect: Pulmonary valve between RV and pulmonary artery.

Q11. How long does one complete cardiac cycle last in a normal adult?

A. 0.5 sec
B. 0.8 sec
C. 1.0 sec
D. 1.5 sec

Answer: B

Explanation:

• A. Incorrect: Too short.
• B. Correct: At 72 beats/min → 0.8 sec/cycle.
• C. Incorrect: Too long.
• D. Incorrect: Too long.

Q12. During atrial systole:

A. Atria contract and push blood into ventricles
B. Ventricles contract
C. Semilunar valves open
D. Blood flows into atria from veins

Answer: A

Explanation:

• A. Correct: Atria contract → ventricles fill with blood.
• B. Incorrect: Ventricular systole comes later.
• C. Incorrect: Semilunar valves open during ventricular systole.
• D. Incorrect: That happens in atrial diastole.

Q13. The “lub” sound of the heart is produced due to closure of:

A. Semilunar valves
B. AV valves (tricuspid and bicuspid)
C. Pulmonary valves
D. Aortic valves

Answer: B

Explanation:

• A. Incorrect: Semilunar valves closure produces “dub.”
• B. Correct: “Lub” = AV valves closure at ventricular systole.
• C. Incorrect: Pulmonary valves are semilunar.
• D. Incorrect: Aortic valve closure produces “dub.”

Q14. The “dub” sound of the heart is caused by closure of:

A. AV valves
B. Semilunar valves
C. Pulmonary veins
D. Coronary arteries

Answer: B

Explanation:

• A. Incorrect: AV valves produce “lub.”
• B. Correct: Semilunar valves closure produces “dub.”
• C. Incorrect: Veins don’t produce sound.
• D. Incorrect: Coronary arteries don’t produce sound.

Q15. Which phase of the cardiac cycle lasts longest?

A. Atrial systole
B. Ventricular systole
C. Ventricular diastole
D. Joint diastole

Answer: D

Explanation:

• A. Incorrect: Atrial systole is brief.
• B. Incorrect: Ventricular systole is shorter.
• C. Incorrect: Ventricular diastole shorter.
• D. Correct: Joint diastole (all chambers relaxed) lasts longest.

Q16. Sinoatrial (SA) node is located in:

A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle

Answer: A

Explanation:

• A. Correct: SA node lies in right atrium wall near vena cava.
• B. Incorrect: Not left atrium.
• C. Incorrect: Not ventricles.
• D. Incorrect: Not ventricles.

Q17. The pacemaker of the heart is:

A. AV node
B. Purkinje fibers
C. SA node
D. Bundle of His

Answer: C

Explanation:

• A. Incorrect: AV node delays impulse.
• B. Incorrect: Purkinje fibers conduct impulse, not initiate.
• C. Correct: SA node generates impulses → pacemaker.
• D. Incorrect: Bundle of His conducts, not initiate.

Q18. Which structure transmits impulse from atria to ventricles?

A. SA node
B. AV node
C. Purkinje fibers
D. Coronary arteries

Answer: B

Explanation:

• A. Incorrect: SA node initiates impulse.
• B. Correct: AV node passes impulse to Bundle of His.
• C. Incorrect: Purkinje fibers distribute to ventricles.
• D. Incorrect: Coronary arteries supply blood, not impulses.

Q19. Which heart chamber pumps blood into systemic circulation?

A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle

Answer: D

Explanation:

• A. Incorrect: Right atrium collects venous blood.
• B. Incorrect: Right ventricle pumps to lungs.
• C. Incorrect: Left atrium receives oxygenated blood.
• D. Correct: Left ventricle → systemic circulation via aorta.

Q20. Cardiac output is defined as:

A. Volume of blood pumped per beat
B. Volume of blood pumped per minute
C. Volume of blood in ventricles
D. Volume of blood in atria

Answer: B

Explanation:

• A. Incorrect: That is stroke volume.
• B. Correct: Cardiac output = stroke volume × heart rate.
• C. Incorrect: That’s end-diastolic volume.
• D. Incorrect: Not atrial volume.

Q21. Stroke volume is approximately:

A. 10 mL
B. 70 mL
C. 150 mL
D. 500 mL

Answer: B

Explanation:

• A. Incorrect: Too low.
• B. Correct: Average stroke volume ≈ 70 mL/beat.
• C. Incorrect: Too high.
• D. Incorrect: Far too high.

Q22. Average cardiac output in an adult is:

A. 1 L/min
B. 2 L/min
C. 5 L/min
D. 10 L/min

Answer: C

Explanation:

• A. Incorrect: Too low.
• B. Incorrect: Too low.
• C. Correct: At rest, cardiac output ≈ 5 L/min.
• D. Incorrect: Too high for rest.

Q23. Bundle of His is responsible for:

A. Initiating heartbeat
B. Conducting impulses from AV node to ventricles
C. Producing “lub” sound
D. Closing AV valves

Answer: B

Explanation:

• A. Incorrect: SA node initiates.
• B. Correct: Bundle of His conducts impulse to Purkinje fibers.
• C. Incorrect: Sounds from valves.
• D. Incorrect: Valves close passively.

Q24. Purkinje fibers function to:

A. Initiate cardiac impulse
B. Transmit impulse rapidly to ventricular muscle
C. Prevent backflow of blood
D. Supply oxygen to heart

Answer: B

Explanation:

• A. Incorrect: SA node initiates impulse.
• B. Correct: Purkinje fibers rapidly spread impulse to ventricles.
• C. Incorrect: Valves prevent backflow.
• D. Incorrect: Coronary arteries supply oxygen.

Q25. Normal heart rate in humans is approximately:

A. 50/min
B. 72/min
C. 100/min
D. 120/min

Answer: B

Explanation:

• A. Incorrect: 50 = bradycardia.
• B. Correct: Average resting HR ≈ 72 beats/min.
• C. Incorrect: 100 = tachycardia.
• D. Incorrect: 120 = higher than normal.

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