What is the second stage of the cardiac cycle referred to?

The second stage of the cardiac cycle is referred to as diastole. During this phase, the heart muscle relaxes after contraction, allowing the chambers of the heart to fill with blood. This is crucial for the heart's ability to pump blood efficiently, as it ensures that the heart has an adequate volume of blood to eject when it returns to the contraction phase.

In diastole, the atria fill with blood from the body and lungs, and the ventricles fill from the atria, preparing the heart for the next contraction. The diastolic phase is essential for maintaining an effective cardiac output, as it sets the stage for the next phase of the cardiac cycle, which is systole—the contraction of the heart muscle.

Understanding diastole is important because it highlights the heart's relaxation phase, which is as vital as the contraction phase (systole) in the overall function of the cardiovascular system.