As the oxygen or air enters to your lung area , it will be going to the heart and will be the one who will be making the blood oxygenated , oxygenated blood is pump from the left atrium to left ventricle , arteries , and then to the capillaries in which oxygenated blood becomes deoxygenated blood , gas exchange. Deoxygenated blood is pump through the veins , right ventricle and right atrium , back to the lung area in which it will become air , or gas , that is carbon dioxide and out of the body or the anus