Explain the purpose of valves in the heart (tricuspid and mitral valves)?

Atrioventricular valves

Explanation:

These are the mitral and tricuspid valves, which are suit between the atria and the ventricles and prevent back flow from the ventricles into the atria during systole. The function of the subvalvular apparatus is to keep the valves from prolapsing into the atria when they close.

The tricuspid valve closes when the right ventricle is full and it keeps the blood from flowing backward into the right atrium when the ventricle contracts. Similarly when the left ventricle is full ,the mitral valve closes and keeps blood from flowing back into the left atrium then the ventricle contracts.