ANATOMY

Detailed explanation-1: -The ventricles contract and all valves are closed, so no blood can be ejected. The ventricular pressure rises considerably without any change in the ventricular blood volume – isovolumic contraction (fig. 1.2).

Detailed explanation-2: -The isovolumetric contraction causes left ventricular pressure to rise above atrial pressure, which closes the mitral valve and produces the first heart sound. The aortic valve opens at the end of isovolumetric contraction when left ventricular pressure exceeds aortic pressure. aortic and pulmonary valves closed.

Detailed explanation-3: -There is a period called isovolumetric contraction during which the ventricles contract but the pulmonary and aortic valves are closed as the ventricles do not have enough force to open them. The atrioventricular valves also remain closed during the isovolumetric contraction period.

Detailed explanation-4: -The correct answer is c) atrioventricular, aortic, and pulmonary valves are closed. Because the volume isn’t changing during isovolumetric relaxation, none of the valves are open as that would allow the volume to change.