Semilunar valves regulate blood flow between which structures?

Semilunar valves regulate blood flow between which structures?

• A. Atria and ventricles
• B. Ventricles and arteries
• C. Atria and arteries
• D. Atria and aorta

Answer: (B)

Semilunar valves regulate the passage of blood from the heart’s ventricles into the great arteries. They sit at the outflow of each ventricle—opening to let blood be ejected into the aorta from the left ventricle and into the pulmonary trunk from the right ventricle, and then closing to prevent backflow during ventricular relaxation. This distinguishes them from the valves between the atria and ventricles, which are the atrioventricular valves. So, the flow controlled by semilunar valves is between the ventricles and the arteries (aorta and pulmonary trunk).

Semilunar valves regulate the passage of blood from the heart’s ventricles into the great arteries. They sit at the outflow of each ventricle—opening to let blood be ejected into the aorta from the left ventricle and into the pulmonary trunk from the right ventricle, and then closing to prevent backflow during ventricular relaxation. This distinguishes them from the valves between the atria and ventricles, which are the atrioventricular valves. So, the flow controlled by semilunar valves is between the ventricles and the arteries (aorta and pulmonary trunk).