Answer:
The answer to the question: Name the phase when the atrioventricular valves and the semilunar valves are all closed during ventricular diastole, would be: the isovolumic, or isovolumetric relaxation.
Explanation:
The systolic and diastolic cycles of the heart ensure that blood is always being circulated around the body from the heart, and from the body to the heart. While systole implies the moments of contraction and active motion of the heart muscles to ensure the correct passage of blood from the four chambers of the heart (atria and ventricles), to and from the body, diastole is the time when either the atria, or ventricles relax to allow the flow of blood into them. To also ensure this process is seamless, there are a series of valves, the atrioventricular valves, or AV valves, and the aortic and pulmonary (semilunar) valves, that will ensure that blood can flow from the atria to the ventricles (AV valves) without flowing back, and that blood will flow towards the body through the aorta, and the lungs, through the pulmonary arteries, through the aortic and semilunar valves, without going back into the ventricles. At one point, when the ventricular diastole begins, there is an early stage known as the isovolumic, or isovolumetric stage, meaning, volumes are pressures are equalized and then both the AV valves and aortic and pulmonary valves are closed only for a bit as the ventricles relax. Not soon later, the AV valves will start opening to allow the gentle flow of blood from the atria, to the ventricles, before actively initiating atrial systole.
