What is the function of AV (atrioventricular valves)?

What is the function of AV (atrioventricular valves)?

Atrioventricular valves are two in number. Mitral valve is between the left atrium and left ventricle. Tricuspid valve is between the right atrium and right ventricle. Mitral valve closes when the left ventricle contracts, to prevent backflow of blood into the left atrium. Tricuspid valve closes when the right ventricle contracts. Hence the blood from the ventricles are able to go out of the heart into the blood vessels during ventricular contraction. Mitral and tricuspid valves open when the ventricles relax, permitting blood to enter the ventricles from the atria. This blood is pumped out when the ventricles contracts next time.

What is the function of atrioventricular valves