How does oxygen pass from alveoli into blood? Is this process passive, like osmosis, or is the membrane active? That is, does it resemble cell membranes, where the integrated membrane proteins are actively transporting chemicals?

Question

Aria Johnson · Accepted Answer

The process that is used while exchanging oxygen and carbon dioxide is diffusion.

When we breathe in, we take in atmospheric air that contains not only molecules of oxygen but also nitrogen and a number of other gases. In alveoli, the concentration of oxygen is higher than in capillaries; similarly, in capillaries, the concentration of carbon dioxide is higher than in alveoli. Because the membranes of alveoli and capillaries are so thin, gases can move from one area of higher concentration to another area of lower concentration in order to maintain equilibrium, or homoeostasis. One is exhaling other gases, like nitrogen.

Addison Adams · Answer

undefined Oxygen passes from alveoli into the blood through a process called passive diffusion. The alveolar membrane is thin and permeable to gases, allowing oxygen to move from an area of high concentration (in the alveoli) to an area of low concentration (in the blood) without the need for energy or active transport mechanisms. Therefore, the process does not resemble cell membranes where integrated membrane proteins are actively transporting chemicals.