Library · Anatomy
Pulmonary alveoli
Make it clearer
The alveoli are the microscopic air spaces where gas exchange takes place. Between the air inside the alveolus and the blood in the capillary there is a very thin barrier, and it's through that barrier that the gases cross from one side to the other: something like a sheet of paper separating two rooms.
That wall isn't made of a single kind of cell. Type I pneumocytes form the surface where the exchange happens; type II pneumocytes make a substance called surfactant and also help repair the epithelium, the layer of cells that lines the wall.
In brief
Alveoli are microscopic air spaces where gas exchange takes place.
A very thin barrier separates alveolar air from capillary blood, and gas exchange happens across it.
Air and blood do not mix: a microscopic wall keeps them apart but is thin enough for gases to cross.
In the alveolar walls, type I pneumocytes form the gas-exchange surface; type II pneumocytes produce surfactant and help repair the epithelium.
Sources (2)
- National Heart, Lung, and Blood InstituteHow the Lungs Work: The Respiratory SystemPublished
- National Center for Biotechnology InformationHistology, Alveolar Cells
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated