What is referred to as systole in cardiac muscle function?

Systole refers specifically to the phase of the cardiac cycle when the heart muscle contracts. During systole, the ventricles of the heart contract to pump blood out to the lungs and the rest of the body. This contraction is essential for maintaining adequate circulation and blood pressure.

Understanding the phases of the cardiac cycle is important in recognizing how the heart functions as a pump. In contrast to systole, diastole is the phase when the heart muscle relaxes and allows the chambers to fill with blood before the next contraction. This distinction highlights the dynamic nature of cardiac function, where the heart alternates between contraction and relaxation to effectively circulate blood.