bild

Human heart. Illustration showing the external anatomy of a human heart, seen from the front. The surface blood vessels are the coronary arteries and veins, bringing oxygenated blood to the heart and removing deoxygenated blood. Across top are parts of the major blood vessels that bring blood to and from the heart. Blood arrives in the vena cava, and is pumped to the lungs in the pulmonary artery. Oxygenated blood from the lungs arrives in the pulmonary vein and is pumped round the body through the aorta. The order of these blood vessels across top, from left to right, is: vena cava, aorta, pulmonary artery and pulmonary vein. (KEYSTONE/SCIENCE PHOTO LIBRARY/ELLA MARU STUDIO / SCIENCE PHOTO LIBRARY)