How do gases move across a respiratory surface?

Gases move across a respiratory surface through the process of diffusion, driven by differences in partial pressure. Oxygen moves from areas of higher concentration in the external environment into the bloodstream, while carbon dioxide, which is at a higher concentration in the blood, diffuses out into the external environment. This exchange occurs across thin, moist membranes, where the gases can easily pass through. Factors such as surface area, thickness of the membrane, and ventilation also influence the efficiency of gas exchange.