Question

Closure of the tricuspid valve:____.

I. Would prevent blood from flowing into the pulmonary trunk.
II. Contributes to the first heart sound (lub).
III. Occurs at the beginning of isovolumetric contraction of the ventricle.
IV. Occurs immediately before the left atrium contracts.

Answer 1

The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously.

Step-by-step explanation: