The mitral and tricuspid valves close after the ventricles are filled with blood because the:
A)chordae tendineae relax, which allows the valves to close.
B)increased pressure in the ventricles pushes the valves to close.
C)trabeculae carneae contract, which pulls the valves closed.
D)reduced pressure in the atria creates a negative pressure that pulls the valves closed.

Question

Quizplus · Accepted Answer

During ventricular relaxation the two atrioventricular valves open and blood flows from the higher-pressure atria to the relaxed ventricles. With increasing ventricular pressure these valves close and prevent backflow into the atria as the ventricles contract.

The Mitral and Tricuspid Valves Close After the Ventricles Are