blood rich in oxygen enters the lungs through the pulmonary artery in where the alveoli within the lungs exchange carbon dioxide and oxygen so the carbon dioxide leaves your body.
The primary function of the respiratory system is to exchange oxygen and carbon dioxide Inhaled oxygen enters the lungs and reaches the alveoli Oxygen passes quickly through this air blood barrier into the blood in the capillaries Similarly carbon dioxide passes from the blood into the alveoli and is then exhaled
