The Opening and Closure of the Atrioventricular and Semilunar Valves

Multiple Choice

The opening and closure of the atrioventricular and semilunar valves is driven by

A) differences in pressure across the valve.
B) contraction of the valve.
C) contraction of the ventricle and atria that pull the valves into place.
D) contraction and relaxation of the valve.
E) contraction of muscles attached to the valves.