In the cardiac cycle,
A)the right atrium and the right ventricle contract simultaneously.
B)the two atria relax while the two ventricles contract.
C)the left atrium contracts before the right atrium.
D)all four chambers of the heart contract at the same time.
E)all four chambers of the heart are in systole at the same time.

Question

Quizplus · Accepted Answer

During the cardiac cycle, the atria and ventricles alternate between contraction (systole) and relaxation (diastole). The cycle begins with both atria contracting simultaneously, followed by both ventricles contracting simultaneously while the atria relax. Therefore, the correct answer is B, where the two atria relax while the two ventricles contract.

In the Cardiac Cycle