What is diffusion in the context of respiratory physiology?

Diffusion, in the context of respiratory physiology, refers specifically to the process of gases being exchanged in the lungs. During breathing, oxygen from the air in the alveoli (the tiny air sacs in the lungs) moves into the bloodstream, while carbon dioxide, which is a waste product produced by the body's cells, moves from the blood into the alveoli to be exhaled. This exchange occurs due to differences in partial pressure; oxygen naturally diffuses from an area of higher concentration (in the alveoli) to an area of lower concentration (in the blood) and vice versa for carbon dioxide.

Understanding this process is fundamental to respiratory physiology because it is critical for maintaining the body's oxygen supply and removing carbon dioxide, thereby supporting cellular respiration and overall metabolic function. The efficiency of gas exchange through diffusion is vital for sustaining life, highlighting its importance in fitness and health as well.