Free Circulation MCQs with Answers
695 Circulation MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The circulatory system covers the chambers, valves and conducting pathway of the human heart, along with the cardiac cycle and control of heartbeat. It compares arteries, veins and capillaries by structure and function, and explains how the lymphatic system returns tissue fluid, transports absorbed fats and supports immunity.
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Read the Circulation notesFree MDCAT chapter notes with key terms695 questions · page 2 of 35
- A. atria
- B. ventricles
- C. valves
- D. septum
Explanation: The right atrium collects deoxygenated blood from the venae cavae and the left atrium receives oxygenated blood from the pulmonary veins.
Correct answer: atria- A. pericardium
- B. interventricular septum
- C. mitral valve
- D. aorta
Explanation: The muscular septum keeps oxygenated and deoxygenated blood completely separate, which is essential for the high efficiency of the…
Correct answer: interventricular septum- A. bicuspid valves
- B. tricuspid valves
- C. semilunar valves
- D. atrioventricular valves
Explanation: Their three crescent shaped pockets fill with blood and snap shut when the ventricles relax, preventing backflow from the great arteries.
Correct answer: semilunar valves- A. pleura
- B. peritoneum
- C. meninges
- D. pericardium
Explanation: The pericardium anchors the heart in the chest and secretes fluid that lubricates its beating.
Correct answer: pericardium- 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…
Correct answer: pulmonary artery, which carries it to the lungs- 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.
Correct answer: never contract at all- 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.
Correct answer: myocardium- 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…
Correct answer: 0.8 second- 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…
Correct answer: the ventricles contract and the semilunar valves open- 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…
Correct answer: semilunar valves- 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.
Correct answer: depolarisation and contraction of the atria- 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…
Correct answer: bundle of His and Purkinje fibres- 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…
Correct answer: close, preventing blood from flowing back into the atria- 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…
Correct answer: systolic pressure while the ventricles contract- A. carry deoxygenated blood only
- B. must collapse when empty
- C. must withstand and smooth out the high pressure of blood from the heart
- D. need to store lymph between meals
Explanation: Each heartbeat stretches the elastic walls, which then recoil and keep blood moving between beats, converting a pulsatile flow into a…
Correct answer: must withstand and smooth out the high pressure of blood from the heart- A. walls are unusually thick
- B. total cross sectional area is enormous
- C. internal pressure is the highest of any vessel
- D. diameter exceeds that of the aorta
Explanation: Although each capillary is microscopic, together they present a huge total area, so the same volume of blood spreads out and slows…
Correct answer: diameter exceeds that of the aorta- A. pulmonary artery
- B. pulmonary vein
- C. aorta
- D. coronary artery
Explanation: The pulmonary artery is the exception to the rule that arteries carry oxygenated blood, since it carries blood to the lungs to be…
Correct answer: pulmonary artery- A. carotid artery
- B. aorta
- C. femoral artery
- D. renal artery
Explanation: The aorta, about 2.5 cm in diameter, receives the entire output of the left ventricle and branches to every organ.
Correct answer: aorta- A. left ventricle
- B. left atrium
- C. right atrium
- D. aorta
Explanation: The venae cavae collect blood from the upper and lower body and deliver it to the right atrium, from where it passes to the right…
Correct answer: right atrium- A. aorta
- B. arteries
- C. arterioles
- D. venae cavae
Explanation: Pressure falls steadily through arteries, arterioles and capillaries as energy is lost to friction, reaching near zero in the great veins.
Correct answer: venae cavae