What characteristic change in myocyte function happens during cardiac diastole?

During cardiac diastole, the primary characteristic change in myocyte function is the relaxation and filling of the ventricles. This phase follows systole, where the heart contracts to pump blood out to the body. In diastole, the heart muscles, or myocytes, relax, allowing the chambers of the heart, particularly the ventricles, to fill with blood from the atria.

As the myocytes relax, the pressure within the ventricles decreases, facilitating the influx of blood from the atria into the ventricles. This filling phase is crucial for the heart’s efficiency and ensures that adequate blood volume is available for the next contraction during systole. The relaxation of myocytes also allows the coronary arteries to be perfused, emphasizing the importance of this phase for both cardiac function and overall coronary health.

The other options, while related to the cardiac cycle, do not accurately describe the primary change in myocyte function during diastole. For instance, increased contractility pertains to the force of contraction, which is more relevant during systole. Similarly, decreased blood flow to the coronary arteries does not occur during diastole; in fact, coronary circulation takes place primarily during this phase due to the relaxation of the heart muscle. Valve closure is