What is the term for the relaxation phase of the heartbeat?

The relaxation phase of the heartbeat is termed "diastole." During diastole, the heart muscles relax, allowing the chambers of the heart to fill with blood. This phase is crucial for ensuring that the heart can adequately receive blood returning from the body and the lungs before the next contraction, or systole, occurs.

Diastole follows systole, the phase where the heart contracts to pump blood out to the rest of the body. Understanding this distinction is important because the efficient functioning of the heart relies on the proper timing and balance between these two phases.

The cardiac cycle encompasses both diastole and systole, describing the overall sequence of events in the heart during a complete heartbeat. An electrocardiogram is a test that measures the electrical activity of the heart, which provides insight into the heart's rhythm and can help diagnose various conditions but does not directly describe the phases of the heartbeat itself.