Valves in heart: (i) In the heart there are a number of openings through which blood passes from one chamber to another.
(ii) These openings are guarded by certain valves which regulate the flow of blood in desired direction. The bicuspid valves and tricuspid valves are present guarding the auriculoventricular apertures in between the auricles and ventricles on the left and right sides respectively. These valves open into the ventricles and prevent the back flow of the blood.
(iii) A set of semilunar valves are also present at the base of aorta in the ventricle. These allows the blood to flow only in direction of an aorta, when the left ventricle contracts.
