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The heart consists of four chambers—two atria (upper chambers) and two ventricles (lower chambers).
Blood passes through a valve before leaving each chamber of the heart. The valves prevent the backward flow of blood.
These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one-way inlets of blood on one side of a ventricle, and one-way outlets of blood on the other side of a ventricle.
Normal valves have three flaps, except for the mitral valve, which has two flaps.
The four heart valves
- Tricuspid valve
Llocated between the right atrium and the right ventricle
- Pulmonary valve
Llocated between the right ventricle and the pulmonary artery
- Mitral valve
Llocated between the left atrium and the left ventricle
- Aortic valve
Located between the left ventricle and the aorta
Heart function
As the heart muscle contracts and relaxes, the valves open and shut, letting blood flow into the ventricles and atria at alternate times.
After the left ventricle contracts, the aortic valve closes and the mitral valve opens, to allow blood to flow from the left atrium into the left ventricle.
As the left atrium contracts, more blood flows into the left ventricle.
When the left ventricle contracts again, the mitral valve closes and the aortic valve opens, so blood flows into the aorta.
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