Deoxygenated blood enters through the right atrium from vena cava, moves through tricuspid valve into right ventricle. This moves up the pulmonary artery to the lungs and oxygenates.Oxygenated blood enters left atrium from pulmonary veins, moves through mitral valve (bicuspid valve) into left ventricle.This moves up the aorta to supply blood to the rest of the body.