The semilunar valves, specifically the aortic and pulmonic valves, prevent backflow of blood from the arteries into the ventricles of the heart. These valves function due to the pressure gradient established during ventricular diastole. As the ventricles relax and pressure decreases, the blood in the aorta and pulmonary artery begins to flow backward towards the heart. This retrograde flow causes the cusps of these valves to fill.
The competency of these valves is critical for maintaining unidirectional blood flow throughout the circulatory system. Efficient closure prevents diastolic backflow, ensuring that cardiac output effectively perfuses the body’s tissues. Dysfunction of these valves, such as in aortic or pulmonic regurgitation, can lead to increased workload on the heart, eventual heart failure, and other serious cardiovascular complications. Understanding the mechanics of valve closure is thus fundamental to diagnosing and managing various heart conditions.
