What occurs after the AV valves are open during ventricular filling?

During the phase of ventricular filling when the atrioventricular (AV) valves are open, blood flows from the atria into the ventricles. Following this, atrial systole occurs. This is the contraction of the atria, which occurs toward the end of the ventricular filling phase. Atrial systole provides an additional push of blood into the ventricles, ensuring they are filled to capacity before the next phase of the cardiac cycle begins.

This contraction is particularly important because it contributes to the final volume of blood in the ventricles, known as end-diastolic volume, which plays a crucial role in the following phase, ventricular systole, where the ventricles will subsequently contract to pump blood to the lungs and the rest of the body. Overall, the timing and coordination of atrial systole following the opening of the AV valves are essential for optimal heart function and efficient blood circulation.