The heart consists of four chambers–two atria (upper chambers) and two ventricles (lower chambers). There is a valve through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood. 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. The four heart valves include the following:
- Tricuspid valve. Located between the right atrium and the right ventricle.
- Pulmonary valve. Located between the right ventricle and the pulmonary artery.
- Mitral valve. Located between the left atrium and the left ventricle.
- Aortic valve. Located between the left ventricle and the aorta.
How do the heart valves function?
As the heart muscle contracts and relaxes, the valves open and close, letting blood flow into the ventricles and out to the body at alternate times. The following is a step-by-step illustration of how the valves function normally in the left ventricle:
- 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.
- The left atrium contracts and more blood flows into the left ventricle.
- When the left ventricle contracts, the mitral valve closes and the aortic valve opens so blood flows into the aorta and out into the systemic circulation to the rest of the body.