Heart Valves

Your heart valves are like doors between your heart chambers. They open and close to allow blood to flow through. They also keep your blood from moving in the wrong direction.

Atrioventricular valves

The atrioventricular (AV) valves open between your upper and lower heart chambers. They include:

• Tricuspid valve: Door between your right atrium and right ventricle.

• Mitral valve: Door between your left atrium and left ventricle.

Semilunar valves

Semilunar (SL) valves open when blood flows out of your ventricles. They include:

• Aortic valve: Opens when blood flows out of your left ventricle to your aorta (artery that carries oxygen-rich blood to your body).

• Pulmonary Valve: Opens when blood flows from your right ventricle to your Pulmonary arteries (the only arteries that carry oxygen-poor blood to your lungs).

The heart has four main valves that regulate blood flow through the chambers and prevent backflow. These valves ensure that blood moves in the correct direction and is pumped efficiently throughout the body. Here's an overview of each heart valve:

1. Tricuspid Valve

• Location: Between the right atrium and the right ventricle.

• Structure: The tricuspid valve has three leaflets or cusps, which is why it is called "tricuspid."

• Function: It prevents the backflow of blood from the right ventricle into the right atrium during ventricular contraction (systole). Blood flows from the right atrium through the tricuspid valve into the right ventricle.

2. Pulmonary Valve

• Location: Between the right ventricle and the pulmonary artery.

• Structure: The pulmonary valve has three semilunar cusps (half-moon-shaped).

• Function: It prevents the backflow of blood from the pulmonary artery into the right ventricle after the ventricle contracts and pumps blood into the pulmonary circulation (to the lungs).

3. Bicuspid (Mitral) Valve

• Location: Between the left atrium and the left ventricle.

• Structure: The bicuspid valve has two leaflets (hence the name "bicuspid"). It is also called the mitral valve because its shape resembles a bishop's mitre (a type of hat).

• Function: It prevents the backflow of blood from the left ventricle into the left atrium when the left ventricle contracts. Blood flows from the left atrium through the mitral valve into the left ventricle.

4. Aortic Valve

• Location: Between the left ventricle and the aorta.

• Structure: The aortic valve has three semilunar cusps.

• Function: It prevents the backflow of blood from the aorta into the left ventricle after the ventricle pumps blood into the aorta, which distributes oxygenated blood to the rest of the body.

Summary of Heart Valve Functions:

• Tricuspid Valve: Prevents backflow from the right ventricle to the right atrium.

• Pulmonary Valve: Prevents backflow from the pulmonary artery to the right ventricle.

• Bicuspid (Mitral) Valve: Prevents backflow from the left ventricle to the left atrium.

• Aortic Valve: Prevents backflow from the aorta to the left ventricle.

Valve Operation (Systole vs. Diastole):

• During systole (contraction), the ventricles contract and pump blood through the pulmonary artery and aorta, causing the atrioventricular valves (tricuspid and mitral) to close to prevent backflow into the atria. The semilunar valves (pulmonary and aortic) open to allow blood to flow out of the heart.

• During diastole (relaxation), the ventricles relax and fill with blood from the atria, causing the semilunar valves to close and the atrioventricular valves to open.

These valves are crucial for maintaining the unidirectional flow of blood and ensuring the heart functions efficiently.