What are heart valves?Valves are flap-like structures that allow blood to flow in one direction. The heart has two kinds of valves, atrioventricular and semilunar valves.
Atrioventricular ValvesThe atrioventricular valves are thin structures that are composed of endocardium and connective tissue. They are located between the atria and the ventricles.
Semilunar ValvesThe semilunar valves are flaps of endocardium and connective tissue reinforced by fibers which prevent the valves from turning inside out. They are shaped like a half moon, hence the name semilunar (semi-, -lunar).
The semilunar valves are located between the aorta and the left ventricle and between the pulmonary artery and the right ventricle.