Heart Valves

What Do Heart Valves Do?

Your heart has four valves that act like doors. Each valve has two jobs. They open to allow blood to flow in or out. They close to prevent blood from flowing where it shouldn’t flow. The heart valves keep blood flowing in one direction through your heart.

Types of Valves

There are two types of valves

Atrioventricular valves—These valves are at the base of the atria. They control blood flow between your heart’s upper and lower chambers. The valve between the right atrium and the right ventricle is the tricuspid valve. The valve between the left atrium and the left ventricle is the mitral valve.

Semilunar valves—These valves are at the top of the ventricles. Semilunar valves control blood flow out of your heart. Blood flows out of the right ventricle to the lungs through the pulmonary valve. Blood flows out of the left ventricle to your body through the aortic valve.

When you listen to your heartbeat through a stethoscope you hear “lubb-dubb, lubb-dubb.” That sound is your heart valves closing. Although your heart has four valves, the valves open and close two at a time. In other words, the atrioventricular valves open and close at the same time. And the semilunar valves open and close at the same time. That’s why you hear only two thumps (“lubb-dubb”) per heartbeat, not four.