Free Human Heart MCQs with Answers

11. The right ventricle pumps blood into the

• A. pulmonary artery, which carries it to the lungs
• B. aorta, which carries it to the body
• C. coronary artery, which feeds the heart muscle
• D. vena cava, which returns it to the heart

Explanation: The right side handles deoxygenated blood and sends it to the lungs for oxygenation, while the left side sends oxygenated blood to the body through the aorta. Remember right to lungs, left to body.

12. The walls of the atria are thinner than those of the ventricles because the atria

• A. pump blood only into the adjacent ventricles
• B. never contract at all
• C. pump blood to the whole body
• D. contain no muscle tissue

Explanation: Atria need only enough force to top up the ventricles below, so their muscle is thin. The left ventricle, which drives blood around the entire body, has the thickest wall of all four chambers.

13. The muscular layer of the heart wall, responsible for its contraction, is the

• A. epicardium
• B. pericardium
• C. myocardium
• D. endocardium

Explanation: The myocardium is cardiac muscle supplied by the coronary arteries, and its death during a heart attack is what damages the pump. The endocardium lines the chambers and the epicardium is the outer surface.

14. At a heart rate of 75 beats per minute, one complete cardiac cycle lasts about

• A. 0.1 second
• B. 0.4 second
• C. 1.2 seconds
• D. 0.8 second

Explanation: Sixty seconds divided by 75 beats gives 0.8 second per cycle, of which atrial contraction takes about 0.1, ventricular contraction 0.3 and the shared relaxation the rest. This arithmetic is a standard MDCAT calculation.

15. During ventricular systole

• A. the ventricles contract and the semilunar valves open
• B. the ventricles relax and fill with blood
• C. the semilunar valves close
• D. the atrioventricular valves open wide

Explanation: Systole means contraction: rising pressure in the ventricles closes the inlet atrioventricular valves and forces open the semilunar valves, ejecting blood into the arteries. Relaxation, diastole, is the opposite phase.

16. The second heart sound, dup, is produced by the closure of the

• A. atrioventricular valves
• B. semilunar valves
• C. coronary valves
• D. pulmonary veins

Explanation: When the ventricles relax, blood trying to flow back snaps the aortic and pulmonary semilunar valves shut, producing the shorter, sharper second sound. The first sound, lubb, comes from the atrioventricular valves closing.

17. In an electrocardiogram, the P wave represents

• A. repolarisation of the ventricles
• B. contraction of the ventricles
• C. depolarisation and contraction of the atria
• D. closure of the heart valves

Explanation: The P wave records the spread of excitation across the atria, which then contract. The QRS complex shows ventricular depolarisation and the T wave ventricular recovery, so each deflection maps to a specific electrical event.

18. After the atrioventricular node, the impulse travels to the apex of the heart along the

• A. sinoatrial node
• B. coronary vein
• C. pulmonary vein
• D. bundle of His and Purkinje fibres

Explanation: The bundle of His carries the impulse down the septum and the Purkinje fibres spread it through the ventricle walls from the apex upwards, squeezing blood out efficiently. This pathway is why the ventricles contract as a unit.

19. During ventricular systole the atrioventricular valves

• A. close, preventing blood from flowing back into the atria
• B. open fully to let blood into the ventricles
• C. dissolve under pressure
• D. contract actively like muscle

Explanation: Rising ventricular pressure lifts the flaps of the tricuspid and bicuspid valves shut, and chordae tendineae anchored to papillary muscles stop them turning inside out. Their closure is the first heart sound.

20. In a blood pressure reading of 120 over 80 mmHg, the figure 120 represents the

• A. pulse rate per minute
• B. systolic pressure while the ventricles contract
• C. diastolic pressure while the heart relaxes
• D. average pressure of the cycle

Explanation: The higher number is recorded at ventricular contraction when arterial pressure peaks, and the lower number is the resting pressure during diastole. Both matter clinically, since sustained high values damage vessels.