NEET Biology: Cardiac cycle Practice Questions
15 free multiple-choice questions on Cardiac cycle (Human Physiology) for NEET Biology, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. Which valve is responsible for preventing the backflow of blood from the left ventricle into the left atrium during ventricular systole?
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Correct answer: A — Mitral valve
The aortic valve controls flow from the left ventricle to the aorta, and the mitral valve controls flow between the left atrium and left ventricle. During ventricular systole, the mitral valve closes to prevent backflow into the atrium, while the aortic valve opens to allow ejection into the aorta. The question refers to the valve preventing backflow into the atrium, which is the mitral valve (incorrectly phrased in options, needs re-evaluation of flow path). Corrected context: The valve preventing backflow from ventricle to atrium during systole is the Mitral valve. Let's rephrase to ensure clarity on the specific valve action related to backflow.
Q2. Which valve controls the flow of blood from the left ventricle into the aorta?
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Correct answer: D — Aortic valve
The aortic valve is situated between the left ventricle and the aorta, regulating blood flow into the systemic circulation.
Q3. The phase where ventricular pressure is higher than atrial pressure, but the AV valves remain closed, is known as:
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Correct answer: D — Isovolumetric contraction
Isovolumetric contraction is the phase where ventricular muscles contract, pressure rises, and all valves are closed (AV valves and semilunar valves).
Q4. Which cardiac event leads to the effective forward flow of blood from the left ventricle into the aorta?
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Correct answer: A — Opening of the aortic valve
The ejection of blood from the left ventricle into the systemic circulation (aorta) occurs when the left ventricle contracts, causing the aortic valve to open and allowing blood to be ejected.
Q5. What defines the transition period between ventricular systole and ventricular diastole in the cardiac cycle?
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Correct answer: D — Isovolumetric relaxation
Isovolumetric relaxation is the period when both the ventricles and atria are closed, and the volume remains constant while pressure is rapidly dropping from the peak systole level.
Q6. Which phase of the cardiac cycle is characterized by the relaxation of the ventricles and filling of the ventricles with blood?
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Correct answer: A — Diastole
Diastole is the phase when the ventricles relax and the atria fill with blood, leading to ventricular filling.
Q7. If the atrial contraction (systole) is omitted, how does the timing of ventricular filling change?
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Correct answer: A — Active filling is hindered
Atrial systole actively pushes the remaining blood into the ventricles, enhancing the overall filling process, which is crucial for efficient filling during diastole.
Q8. The phase of the cardiac cycle when the pressure in the ventricles is greater than the pressure in the atria is known as:
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Correct answer: D — Ventricular Systole
Ventricular systole occurs when ventricular pressure exceeds atrial pressure, leading to ventricular contraction and blood ejection.
Q9. Which event immediately follows the closure of the AV valves during the cardiac cycle?
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Correct answer: C — Ventricular diastole
After the AV valves (mitral and tricuspid) close, the ventricles begin to fill with blood, which constitutes ventricular diastole.
Q10. The opening of the semilunar valves (aortic and pulmonary) is primarily triggered by the increase in pressure within which chamber?
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Correct answer: A — Left Ventricle
The ejection phase occurs when the pressure in the ventricles exceeds the pressure in the great arteries, causing the semilunar valves to open and blood to be ejected.
Q11. Which set of valves are closed during ventricular systole (contraction)?
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Correct answer: D — Mitral and Tricuspid valves
During ventricular systole, the AV valves (Mitral and Tricuspid) are closed to prevent backflow into the atria while the semilunar valves are open.
Q12. The primary event that initiates the contraction phase of the cardiac cycle is:
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Correct answer: D — Impulse from the SA node
The electrical impulse generated by the Sinoatrial (SA) node acts as the pacemaker, initiating the electrical events that lead to ventricular contraction.
Q13. During ventricular systole, what action occurs regarding the AV valves (mitral and tricuspid valves)?
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Correct answer: C — They close
During ventricular systole (contraction), the pressure in the ventricles rises, forcing the AV valves to close to prevent backflow.
Q14. Which chamber contracts to eject blood into the systemic circulation?
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Correct answer: D — Left ventricle
The left ventricle has the thickest muscular wall and generates the highest pressure to pump oxygenated blood into the systemic circulation.
Q15. The opening of the AV valves (mitral and tricuspid) is directly caused by the pressure difference between which chambers during the cardiac cycle?
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Correct answer: B — Atrial pressure and ventricular pressure
The opening of the AV valves occurs when ventricular pressure exceeds atrial pressure, allowing blood to flow from the atria into the ventricles.
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