What is the function of semilunar valves in the circulatory system?

The role of semilunar valves is primarily to prevent backflow of blood from the arteries into the ventricles of the heart. These valves are located at the exits of the left and right ventricles, where they lead into the aorta and pulmonary artery, respectively. When the heart contracts and pumps blood out, the semilunar valves open to allow blood to flow into these large arteries. When the heart relaxes, these valves close tightly, preventing blood from flowing backward into the ventricles.

This is crucial for maintaining unidirectional blood flow and ensuring that the heart effectively pumps blood throughout the body without losing pressure. Correct functioning of semilunar valves is vital for maintaining the efficiency of the circulatory system, ensuring that oxygenated blood reaches the tissues while deoxygenated blood is transported to the lungs.

Other answers relate to different functions: preventing blood from entering the heart chambers pertains more to the role of atrioventricular valves, regulating blood pressure involves broader physiological mechanisms, and facilitating nutrient exchange is associated with the capillary networks, not the heart valves.