The cardiac cycle refers to the sequence of events that occur during one complete heartbeat. It involves the contraction and relaxation of the heart muscles, specifically the atria and ventricles, which allows for the pumping of blood throughout the body.
The cardiac cycle consists of two main phases: systole and diastole.
1. Systole: During systole, the heart muscles contract and the chambers of the heart push blood forward. This phase can be further divided into two stages:
- Atrial Systole: The atria contract and push blood into the ventricles. This contributes to the filling of the ventricles.
- Ventricular Systole: The ventricles contract and pump blood out of the heart. The aortic and pulmonary valves open, allowing blood to be ejected into the aorta and the pulmonary artery, respectively.
2. Diastole: During diastole, the heart muscles relax and the chambers refill with blood. Similar to systole, diastole can be divided into two stages:
- Early Diastole: The ventricles relax and begin to fill with blood from the atria. The aortic and pulmonary valves close to prevent blood from flowing back into the ventricles.
- Late Diastole: The atria continue to contract and push any remaining blood into the ventricles, completing the filling process.
Overall, the cardiac cycle ensures the continuous flow of blood through the heart and arteries, delivering oxygen and nutrients to tissues and organs, while also removing waste products.
Describe cardiac cycle
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