Which term refers to the expansion phase of the heart cycle?

The term that refers to the expansion phase of the heart cycle is diastole. During diastole, the heart muscle relaxes and the chambers of the heart, specifically the ventricles, fill with blood that is entering from the atria. This phase is crucial because it allows the heart to receive oxygenated blood from the lungs and deoxygenated blood from the body, preparing for the next contraction.

The diastolic phase is essential for ensuring that the heart has adequate blood volume to pump effectively during systole, the contraction phase. The relaxation that occurs during diastole is necessary for proper heart function, as it allows the heart to refill and maintain an efficient blood flow throughout the body. Understanding the role of diastole, along with systole, is key to comprehending cardiac physiology and the overall function of the cardiovascular system.