Heart, illustration. The heart is a hollow sac of muscular tissue that pumps blood around the body. The aorta (curved, upper centre) carries blood to the body. Three smaller arteries are seen branching off it. To the left of the aorta is part of the vena cava vein. This vein carries deoxygenated blood into the heart from the body. This blood then travels from the heart to the lungs (where it obtains oxygen) and back to the heart through the pulmonary artery (right of the aorta). Illustration from Traite d' Anatomie humaine By L. Testut (1905) Paris.