Illustration of a section through a human heart, showing its internal anatomy. The internal chambers of the heart consist of the left (lower right) and right (bottom left) ventricles, which are separated from the left atrium (upper right) and right atrium (centre-left) by the mitral and tricuspid valves respectively. Deoxygenated blood enters via the vena cava vein (top left) and is pumped into the right atrium (left). Blood leaves the left ventricle (right) for the lungs via the pulmonary artery (top right). Oxygenated blood leaves the heart via the aorta.