Washington Master Esthetics Practice Exam

What role do the semilunar valves play in the heart?

1. They prevent backflow of blood into the atria.

2. They regulate blood flow between the ventricles and aorta or pulmonary artery.

3. They separate the left and right ventricles.

4. They connect the heart to the lungs.

The correct answer is: They regulate blood flow between the ventricles and aorta or pulmonary artery.

Semilunar valves are crucial components located at the exit points of the heart's ventricles. Their primary function is to regulate blood flow from the ventricles into the major arteries—specifically, the aorta and the pulmonary artery. When the ventricles contract during systole, these valves open, allowing blood to be ejected into the aorta (which carries oxygenated blood to the body) and into the pulmonary artery (which carries deoxygenated blood to the lungs). After the ventricles finish contracting and the pressure within them falls, the semilunar valves close to prevent any backflow of blood, thus ensuring a one-way flow of blood and maintaining the efficiency of the circulation system. This role differs from other structures of the heart. For instance, the atrioventricular valves are responsible for preventing backflow into the atria, while the septum separates the left and right ventricles. Additionally, while the heart connects to the lungs, that connection is achieved through the pulmonary vessels rather than directly by the semilunar valves.