There are four valves within your heart. They are the mitral, tricuspid, aortic and pulmonic valve.
The mitral valve and tricuspid valve lie between the atria (upper heart chambers) and the ventricles (lower heart chambers). The aortic valve and pulmonic valve lie between the ventricles and the major blood vessels leaving the heart.
As blood leaves each chamber of the heart, it passes through a valve. Your heart valves make sure that blood flows in only one direction through your heart.
A Closer Look at the Valves
The valve is made of strong, thin pieces or flaps of tissue called leaflets.
The leaflets are attached to and supported by a ring of tough fibrous tissue called the annulus. The annulus helps to provide support and maintain the proper shape of the valve.
The valve leaflets can be compared to doors opening and closing. While the annulus functions as the door frame.
The leaflets of the mitral and tricuspid valve are also supported by tough, fibrous strings called chordae tendineae. These are similar to the strings supporting a parachute. The chordae tendineae extend from the valve leaflets to small muscles, called papillary muscles, which are part of the inside walls of the ventricles. The chordae tendineae and papillary muscles keep the leaflets stable against any backward flow of blood.
How Valves Work
The right and left sides of the heart work together to pump blood throughout the whole body. The four heart valves make sure that blood always flows freely in a forward direction and that there is no backward leakage.
1. Blood flows from your right and left atria into your ventricles through the open mitral and tricuspid valves.
2. When the ventricles are full, the mitral and tricuspid valves shut. This prevents blood from flowing backward into the atria while the ventricles contract (squeeze).
3. As the ventricles begin to contract, the pulmonic and aortic valves are forced open and blood is pumped out of the ventricles through the open valves into the pulmonary artery toward the lungs, and the aorta, to the body.
4. When the ventricles finish contracting and begin to relax, the aortic and pulmonic valves snap shut. These valves prevent blood from flowing back into the ventricles.
This pattern is repeated, causing blood to flow continuously to the heart, lungs and body.