The first of the heart sounds is caused by the closing of the semilunar valves.

Name: The first of the heart sounds is caused by the closing of the semilunar valves.
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Question

Quizplus · Accepted Answer

The first heart sound (S1) is caused by the closure of the atrioventricular valves (mitral and tricuspid), not the semilunar valves (pulmonary and aortic). The second heart sound (S2) is caused by the closure of the semilunar valves.

The First of the Heart Sounds Is Caused by the Closing