Which period of the cardiac cycle includes the emptying of blood from the atria to the ventricles?

The period of the cardiac cycle that involves the emptying of blood from the atria to the ventricles is atrial systole. During this phase, the atria contract, which pushes blood into the ventricles. This contraction occurs after the atria have filled with blood during the previous diastole phase, where the atria are relaxed and allowing blood to flow from the body and lungs.

Atrial systole is crucial for ensuring that the ventricles are adequately filled with blood before they contract to pump it out to the lungs and the rest of the body. This process is essential for maintaining efficient circulation and ensuring that the heart functions effectively.

In contrast, atrial diastole refers to the period when the atria are relaxed and filling with blood, while ventricular systole is when the ventricles contract to eject blood out of the heart. Ventricular diastole is when the ventricles relax and fill with blood from the atria. Each of these phases plays a critical role in the overall cardiac cycle, but the specific action of emptying blood from the atria to the ventricles is distinctly associated with atrial systole.