The heart has four valves. The mitral valve, the tricuspid valve, the pulmonary valve and the aortic valve. The mitral and the tricuspid valves, also known as the atrioventricular valves, are located between the top chambers of the heart, the atria, and the lower chambers of the heart, the ventricles. The aortic and pulmonary valves, are located between the ventricles and the arteries that emerge from the heart. These valves are also known as the semilunar valves.
The heart valves regulate blood flowing through the heart. After the atria fill with blood, the mitral and tricuspid valves open to allow the blood to flow from the atria into the ventricles. When the ventricles contract, the mitral and tricuspid valves close while the blood is pumped outward through the pulmonary and aortic valves to the lungs and body.