What are Ventricles "Doing" During Atrial Contraction

Question

What are ventricles "doing" during atrial contraction?
A) Pumping blood into the great vessels
B) Closing their AV valves
C) Relaxing
D) Opening their semilunar valves

Accepted Answer

During atrial contraction, the ventricles are relaxing. This is because the atria are contracting to push blood into the ventricles, causing them to fill with blood and prepare for their own contraction during ventricular systole. The semilunar valves are closed during this time to prevent backflow of blood into the ventricles. The AV valves are also closed to prevent blood from flowing back into the atria. Thus, the best option is C - Relaxing.