Pulmonary heart valve

Pulmonary heart valve is a semilunar valve that lies between the right ventricle and the pulmonary artery in the heart. It is one of the two semilunar valves of the heart, the other being the aortic valve. The valve is composed of three cusps that are shaped like half-moons (semilunar). These cusps are made of strong fibrous tissue and are attached to the pulmonary artery wall.

Structure

The pulmonary valve is located at the base of the pulmonary artery. This valve has three cusps, each a half-moon shape. The cusps are quite thin and pliable, made of a layer of endocardium reinforced with additional fibrous tissue. The cusps are attached at their bases to a ring of fibrous tissue, which is in turn fused to the myocardium at the base of the pulmonary artery.

Function

The function of the pulmonary valve is to prevent backflow of blood from the pulmonary artery into the right ventricle during diastole, the phase of the cardiac cycle when the heart relaxes after contraction. When the right ventricle contracts during systole, the increased pressure pushes the cusps of the pulmonary valve open, allowing blood to exit the right ventricle and enter the pulmonary artery. When the right ventricle relaxes during diastole, the pressure in the ventricle drops. Blood starts to flow back towards the ventricle, filling the cusps of the pulmonary valve and causing them to close. This prevents blood from flowing back into the right ventricle.

Clinical significance

Diseases of the pulmonary valve include pulmonary valve stenosis and pulmonary valve regurgitation. Pulmonary valve stenosis is a condition in which the flow of blood from the right ventricle to the pulmonary artery is obstructed by a narrowing (stenosis) of the pulmonary valve. Pulmonary valve regurgitation is a condition in which the valve does not close properly, allowing blood to flow back into the right ventricle during diastole.

See also

• Heart valve
• Pulmonary circulation
• Cardiac cycle

Pulmonary heart valve Resources
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