<P> From the right ventricle, blood is pumped through the semilunar pulmonary valve into the left and right main pulmonary arteries (one for each lung), which branch into smaller pulmonary arteries that spread throughout the lungs . </P> <P> The pulmonary arteries carry deoxygenated blood to the lungs, where carbon dioxide is released and oxygen is picked up during respiration . Arteries are further divided into very fine capillaries which are extremely thin - walled . The pulmonary vein returns oxygenated blood to the left atrium of the heart . </P> <P> The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle . This blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle . From the left ventricle the blood passes through the aortic valve to the aorta . The blood is then distributed to the body through the systemic circulation before returning again to the pulmonary circulation . </P> <P> From the right ventricle, blood is pumped through the semilunar pulmonary valve into the left and right main pulmonary arteries (one for each lung), which branch into smaller pulmonary arteries that spread throughout the lungs . </P>

Where does blood leaving the left ventricle go