Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Alveolar-capillary barrier
Introduction
Overview
Overview
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.[1]
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.
External links
External links
- Template:UCDavisOrganology – “Mammal, lung vasculature (EM, High)”
- Template:EmbryologySwiss
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]