What term refers to the contraction of heart muscle?

The term that refers to the contraction of heart muscle is systole. During systole, the heart muscle fibers contract, which leads to the pumping of blood out of the heart chambers. This phase is crucial in the cardiac cycle, as it generates the pressure necessary to propel blood through the circulatory system to the lungs and the rest of the body.

Systole specifically encompasses the events that occur when the ventricles contract to push blood away from the heart. This is followed by diastole, which is the relaxation phase when the heart chambers fill with blood. Understanding the distinction between systole and diastole is essential, as they work together to maintain effective blood circulation.

The other terms listed, such as ventricular filling and isovolumetric contraction, represent specific phases or events within the cardiac cycle but do not denote the generic contraction of heart muscle that systole encompasses. Ventricular filling occurs during diastole when the heart chambers fill with blood, and isovolumetric contraction refers to a phase in systole when the ventricles contract with no volume change because all heart valves are closed, occurring before the ejection of blood. Thus, systole is the overarching term that succinctly defines the contraction phase of the heart.