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The valves allow the flow, and prevent the backflow, of blood in the heart chambers, ensuring that the muscle contractions force the blood in the proper direction.
There is a valve in the middle of the heart that keeps the blood going where it is supposed to go. There are also valves in the veins, but that's a different story.
There are four valves of two types (atrioventricular valves and semilunar valves). The four valves are : Tricuspid Valve (between the right atrium and the right ventricle) Pulmonary Valve* (semilunar...