TY - CHAP M1 - Book, Section TI - Diffusion of Gases A1 - Levitzky, Michael G. A2 - Levitzky, Michael A2 - McDonough, Kathleen A2 - Kaye, Alan David A2 - Hall, Stanley PY - 2021 T2 - Clinical Physiology in Anesthetic Practice AB - Diffusion of a gas occurs when there is a net movement of molecules from a region in which that particular gas exerts a high partial pressure to a region in which it exerts a lower partial pressure. Movement by diffusion therefore differs from the movement of gases through the conducting airways, which occurs by bulk flow (mass movement or convection). During bulk flow, gas movement results from differences in total pressure, and molecules of different gases move together along the total pressure gradient. During diffusion, gas movement occurs in both directions, but because of its greater number of molecules per unit volume, the area of higher partial pressure has proportionately more random departures. The net movement of gas therefore depends on the partial pressure difference between the two areas. The rate of diffusion is temperature-dependent because random molecular movement increases at higher temperatures. In a static situation, diffusion continues until no partial pressure differences exist. In the lungs, oxygen and carbon dioxide continuously enter and leave the alveoli, so such an equilibrium is never reached. SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/03/29 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1175535120 ER -