vevssirkulasjonen

Vevssirkulasjonen, also known as the cardiac cycle, is the sequence of events that occurs during one complete heartbeat. It consists of two main phases: systole and diastole. Systole is the phase of contraction, where the heart muscles (myocardium) contract to pump blood out of the heart chambers. Diastole is the phase of relaxation, where the heart muscles relax to allow blood to flow into the chambers.

The cardiac cycle begins with atrial systole, where the atria (upper chambers) contract to push blood into the ventricles (lower chambers). This is followed by ventricular systole, where the ventricles contract to pump blood out of the heart and into the arteries. The cycle ends with ventricular diastole, where the ventricles relax to allow blood to flow back into them from the veins.

The cardiac cycle is regulated by the electrical activity of the heart, which is initiated by the sinoatrial (SA) node. The SA node generates electrical impulses that spread through the heart, causing the atria to contract first, followed by the ventricles. The cycle is completed when the SA node generates the next impulse.

The cardiac cycle is essential for the circulation of blood throughout the body. It ensures that oxygen and nutrients are delivered to tissues and that waste products are removed. The efficiency of the cardiac cycle can be affected by various factors, including heart rate, blood pressure, and the health of the heart muscles.