What is the meaning of diastolic in the context of heart function?

In the context of heart function, diastolic refers to the phase of relaxation of the heart muscle. During this phase, the heart chambers, particularly the ventricles, fill with blood after contraction. This is an essential part of the cardiac cycle, allowing the heart to receive blood from the body and lungs in preparation for the next contraction or systole.

The understanding of diastolic function is crucial as it affects overall cardiac efficiency and blood flow. If the heart does not relax properly, it may lead to conditions such as diastolic dysfunction, which can result in heart failure and other complications.

While the other options might refer to different aspects of heart function—e.g., contraction relates to systole, tension could describe the state of the heart muscle during work, and expansion might vaguely evoke heart chambers' capacity during filling—they do not accurately define diastolic function as the phase of relaxation.