What occurs during late diastole concerning the atria?

During late diastole, the primary activity of the atria is to contract in order to push the blood into the ventricles. This contraction is known as the A-wave, which is a reflection of atrial systole. This phase comes just before the ventricles begin their contraction, ensuring that they are filled to their optimal capacity with blood.

As the atria contract, they effectively increase the pressure in the atria, prompting the remaining blood in the atria to flow into the relaxed ventricles. This action is crucial in maximizing ventricular filling, particularly during the final phase of the diastole before the heart transitions into systole, where the ventricles will then contract to pump blood throughout the body.

Other potential activities of the atria, such as relaxing, remaining at rest, or experiencing pressure without contraction, do not accurately describe the physiological events of late diastole. The correct understanding of this phase is integral for recognizing the overall cardiac cycle and the roles of different heart chambers within that cycle.