Heart anatomy, artwork. The heart is a hollow muscle that pumps blood around the body. Deoxygenated blood from the body is carried into the right side of the heart (left) via the vena cava (blue, top right). From here, the blood travels into the lungs via the pulmonary arteries (blue, upper centre), where it is oxygenated. The blood is then carried into the left side of the heart (right) via the pulmonary veins (red, upper centre), before travelling back into the body via the aorta (red, top), where it can exchange oxygen for carbon dioxide and start the cycle all over again. The blood vessels on the surface of the heart supply it with oxygen (red) and take away its waste products (blue).