Valves are flap-like structures present in heart that allow blood to flow in one direction. The valves control the flow of blood through the heart by opening and closing during the contractions of the heart. The opening and closing functions of the valves are controlled by pressure differences generated within the heart, as well as some muscles located within the heart. The heart has two kinds of valves, atrioventricular and semilunar valves.
- The two atrioventricular (AV) valves, which are between the atria and the ventricles, are the mitral valve and the tricuspid valve.
- The two semilunar (SL) valves, which are in the arteries leaving the heart, are the aortic valve and the pulmonary valve.
Thus there are four valves in all.