Arteries carry oxygenated blood away from the heart to all parts of the body. The left ventricle pumps oxygenated blood out of the heart into the aorta, the largest artery, which is responsible for carrying blood to all parts of the body in order to receive oxygen. However, the pulmonary artery carries deoxygenated blood away from the right side of the heart to the lungs. This blood is high in carbon dioxide and must be transported to the lungs in order to become oxygenated. This oxygenated blood passes into the pulmonary veins which return the oxygenated blood to the left atrium of the heart. Then, the blood passes through a valve to the left ventricle and is pumped back out to the body through the aorta once again.