A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart. A heart valve opens or closes incumbent upon differential pressure on each side.
The four valves in the heart are:
The two atrioventricular (AV) valves, which are between the atria and the ventricles, are the mitral valve and the tricuspid valve.
The two semilunar (SL) valves, which are in the arteries leaving the heart, are the aortic valve and the pulmonary valve.
A form of heart disease occurs when a valve malfunctions and allows some blood to flow in the wrong direction. This is called regurgitation.
3D reconstruction of the heart as viewed from the apex towards the valves, image flipped 180° relative to illustration above. Pulmonary valve not visible, leaflets of the tricuspid and aortic valves only partly visible. To the left two images in 2D from the same dataset, showing tricuspid and mitral valves (above) and aortal and mitral valve (below).
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