What does diffusion refer to in the context of the respiratory system?

Diffusion, in the context of the respiratory system, specifically refers to the process by which gases are exchanged in the lungs. This occurs primarily in the alveoli, where oxygen from the air inhaled into the lungs moves into the bloodstream, while carbon dioxide from the blood is released into the alveoli to be exhaled. This exchange relies on the concentration gradient; oxygen diffuses from an area of higher concentration in the alveoli to a lower concentration in the blood, while carbon dioxide does the opposite.

Understanding diffusion helps clarify how essential gases are transported in the body and underlines the importance of a healthy respiratory system. It is a vital mechanism that ensures that our cells receive the oxygen they require for metabolism and that metabolic waste is removed efficiently.