What is the first stage of the cardiac cycle known as?

The first stage of the cardiac cycle is known as diastole. During this phase, the heart muscles relax, allowing the chambers of the heart, specifically the atria and ventricles, to fill with blood. Proper understanding of this phase is crucial because diastole sets the stage for efficient blood circulation, preparing the heart for the next phase, which is systole, where the heart contracts and pumps blood out of the chambers.

In contrast, systole refers specifically to the phase of contraction following diastole. Repolarization and polarization pertain to electrical changes in cardiac muscle cells rather than the mechanical phases of the cardiac cycle. This understanding is fundamental in cardiac physiology and helps in recognizing the importance of each component in maintaining effective heart function.