physiology of gas exchange

Gas exchange occurs in the lungs, where oxygen from inhaled air passes into the blood, and carbon dioxide from the blood is expelled. Tiny sacs called alveoli provide a large surface area, allowing oxygen to diffuse across thin walls into the blood into tiny blood vessels called capillaries. Simultaneously, carbon dioxide moves from the blood into the alveoli to be exhaled. This process is driven by differences in gas concentrations and relies on simple diffusion, essential for supplying oxygen to body tissues and removing waste carbon dioxide produced by metabolism.