Alveolar-capillary barrier
- Alveolar-capillary barrier
Infobox Anatomy
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Caption = Gaseous exchange in the lung.
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MeshName = Blood-Air+Barrier
MeshNumber = A04.411.715.025
DorlandsPre = m_08
DorlandsSuf = 12522385
The alveolar-capillary barrier (or membrane, or blood-air barrier) exists in the gas exchanging region of the lungs. It exists to prevent air bubbles from forming in the blood, and from blood entering the alveoli. It is formed by the type 1 pneumocytes of the alveolar wall, the endothelial cells of the capillaries and the basement membrane between the two cells. The barrier is permeable to molecular oxygen, carbon dioxide, carbon monoxide and many other gases. [citebook|title=Physiology for Health Care and Nursing|author= Sheenan Kindlen|yeat=2003|publisher=Elsevier Health Sciences| pages=130|id=ISBN 0443071160|url=http://books.google.com/books?id=UmPzgwVbnBoC&pg=PA130&ots=-5bFL4pqz_&dq=%22Alveolar-capillary+barrier%22&as_brr=3&ei=Hqa8RtieNIXy6gKu1KjEBQ&ie=ISO-8859-1&output=html&sig=MWd03S-rw3zcC2KirZWc1Zwmwbc] This blood gas barrier is extremely thin (600-800 nm; some places merely 200 nm) so as to allow sufficient oxygen diffusion, yet it is extremely strong. This strength comes from the type 4 collagen in between the endothelial and epithelial cells. Damage can occur to this barrier at pressures of around 40mmhg. Failure of the barrier is often seen in racehorses and other domesticated horses due to exercise induced blood pressure rising above normal.
ee also
* Pulmonary vein
References
External links
* - "Mammal, lung vasculature (EM, High)"
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