Oxygen Transport: Understanding Diffusion from Alveoli to Capillaries

Oxygen moves from the alveoli to capillaries through the process of diffusion. Diffusion is the net movement of molecules or ions from a region of higher concentration to a region of lower concentration. In the alveoli, oxygen concentration is higher than in the capillaries, so oxygen diffuses across the alveolar-capillary membrane into the capillaries.