Animation of a human heart, sectioned to show the flow of blood. Deoxygenated blood from the body enters through the right atrium (upper right), before passing through the tricuspid valve to the right ventricle (lower right), from where it is pumped through the pulmonary valve to the pulmonary artery and to the lungs. The newly oxygenated blood from the lungs returns to the heart through the left atrium, passing through the mitral valve to the left ventricle. The left ventricle is larger and mor