Blood flow comes from the entire body into the superior and inferior vena cava then into the right atrium of the heart. Then the blood passes through the tricuspid valve into the right ventricle. Then the blood passes through the pulmonic valve to the lungs to get oxygenated. The blood then returns to the heart through the pulmonary veins into the left atrium. The blood then passes through the mitral valve / bicuspid valve into the left ventricle. Then the blood exists the heart through the aortic valve to the entire body.