Gas Exchange in the Respiratory System: Where and How It Occurs

Gas exchange in the respiratory system occurs in the alveoli, which are tiny air sacs in the lungs. Oxygen from the air we breathe diffuses through the walls of the alveoli and into the surrounding capillaries, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide from the blood diffuses into the alveoli and is exhaled out of the body. This process is facilitated by the thin walls of the alveoli and the surrounding capillaries, which allow for efficient exchange of gases between the lungs and the bloodstream.