The pulmonary system starts as with the single pulmonary artery that leaves the right ventricle and shortly after divides into the right and left branches. Each of these branches enter the lungs and divide to ultimately be involved in the gaseous exchange that takes place in the lungs. The aorta leaves the heart via the left ventricle and very shortly after divides to provide the two coronary arteries that supply blood to the heart itself. Shortly after that the first of many divisions occur. Blood from the aorta is supplied to the head, the thoracic region including the wings, the abdominal region including the legs and tail.