NEET Zoology Cardiac Cycle Assertion Reason Question
Assertion (A): During ventricular diastole, the semilunar valves close to prevent backflow of blood into the ventricles. | Reason (R): The closure of semilunar valves occurs due to the higher pressure in the aorta and pulmonary artery compared to the ventricular pressure.
Both A and R are true and R explains A.
Both A and R are true but R does not explain A.
A is true but R is false.
A is false.
Correct Answer
Detailed Explanation
The NCERT context states that during ventricular diastole, the ventricular pressure falls, causing the semilunar valves to close to prevent backflow of blood. This happens because the pressure in the aorta and pulmonary artery is higher than in the ventricles.
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