What physiological change occurs during diastole?

During diastole, the physiological change that occurs is the relaxation of the heart chambers, allowing them to fill with blood. This phase is critical for the heart’s functioning as it prepares for the subsequent contraction during systole. Specifically, the pressure in the ventricles decreases, leading to the opening of the atrioventricular valves, which enables blood to flow from the atria into the relaxed ventricles. This filling process is essential for ensuring that enough blood is present in the heart to be pumped out during the next contraction.

The choice about the heart chambers contracting is not applicable during diastole, as contraction occurs during systole. Similarly, while electrical impulses are indeed important for heart function, the initiation in the AV node does not specifically relate to the diastolic phase itself but rather to the coordination of contraction. Lastly, the closing of the valves occurs primarily during the transition to systole to prevent backflow, and this does not define the relaxation and filling that characterizes diastole. Thus, the correct understanding focuses on the relaxation and filling process specific to diastole.