Blood must be pumped in one direction. To keep the blood flowing in the right direction, the heart has four valves, two on the right side and two on the left.
The tricuspid valve lies between the right atrium and the right ventricle.
The pulmonic valve lies between the right ventricle and the pulmonary artery.
The mitral valve lies between the left atrium and the left ventricle.
The aortic valve lies between the left ventricle and the aorta.
