One complete heart beat, combining the contraction and relaxation phases is known as the:

One complete heart beat, combining the contraction (systole) and relaxation (diastole) phases, is known as the cardiac cycle. The cardiac cycle consists of two main phases: systole, where the heart muscle contracts to pump blood out of the chambers, and diastole, where the heart muscle relaxes to allow the chambers to fill with blood. This sequence ensures that oxygenated blood is circulated throughout the body and deoxygenated blood is sent to the lungs for oxygenation.