Final answer:
The process of ventricular diastole involves the occlusion of semilunar valves, adjustment of volume and ventricular filling with atrioventricular valves, and the clamping of atrioventricular valves when optimal filling is achieved. The early phase, called isovolumic ventricular relaxation phase, is isovolumetric as there is no change in blood volume. The second phase, ventricular ejection phase, is when the ventricles contract, pumping blood out of the heart.
Step-by-step explanation:
In the process of ventricular diastole, there is gradual occlusion of the semilunar valves, volume and ventricular filling are adjusted with the atrioventricular valves. When optimal filling is achieved, the atrioventricular valves are clamped and you're off!
In the early phase of ventricular diastole called the isovolumic ventricular relaxation phase, pressure within the ventricles drops, causing blood to flow back toward the heart. The semilunar valves close to prevent backflow, while the atrioventricular valves remain closed. This phase is isovolumetric because there is no change in the volume of blood in the ventricle.
In the second phase of ventricular systole called the ventricular ejection phase, pressure generated by the ventricular muscle exceeds the pressures in the pulmonary trunk and aorta, leading to blood being pumped out of the heart. This is when the pulmonary and aortic semilunar valves open and stroke volume, the amount of blood pumped by the ventricles, is determined.