This image shows an external view of some of the great vessels that leave the heart. The pulmonary trunk, carrying blood low in oxygen and high in carbon dioxide to the lungs, exits the right ventricle and curves toward the left side of the heart.  The pulmonary trunk soon branches into the left and right pulmonary arteries which deliver blood to the left and right lungs, respectively. The aorta leaves the left ventricle and carries oxygenated systemic blood to all parts of the body.  It is the start of the systemic circulation.