Download Biophysics course - 2012-section3f

Electron micrograph of an alveolar
wall showing the path for diffusion of
O2 and CO2. The thin side of the
alveolar wall barrier (short arrows);
alveolar capillary (C), red blood cell
(EC). The thick side of the gas
exchange barrier has an accumulation
of fibrils and matrix (FB). The
alveolar epithelium (EP) is separate
from
the
alveolar
capillary
endothelium (EN) by interstitial space
(IN). As long as the red blood cells
are flowing, O2 and CO2 diffusion
probably occurs across both sides of
the air-blood barrier. Gas exchange
pathway: 2 -tissue barrier; 3 - blood
plasma; and 4 - erythrocyte. (8600
magnification).
Schematic showing the exchange surface of alveoli.
The path is very small < 1 µm.
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