During atrial systole in the cardiac cycle of humans, the state of ventricles, atrioventricularvalves and semilunar valves is
Correct answer: B. B
- A. A
- B. B
- C. C
- D. D
Explanation
During atrial systole, the atria contract to push blood into the ventricles. Therefore, the ventricles are relaxed at this stage. The atrioventricular valves (tricuspid and mitral valves) must be open to allow blood to flow from the atria into the ventricles. Meanwhile, the semilunar valves (aortic and pulmonary valves) remain closed to prevent blood from flowing back into the ventricles from the arteries. Hence, Option B is correct. Options A, C, and D describe states that do not occur during atrial systole.
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About Cardiac Cycle and Heartbeat
The cardiac cycle describes atrial systole, ventricular systole and diastole, including pressure changes, blood movement and the opening or closing of heart valves. It also covers the conduction pathway from the sinoatrial node through the atrioventricular node, bundle of His and Purkinje fibres, and relates these events to heartbeat sounds.
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