Left Lung
After passing through many fine braches of the pulmonary artery, you arrive
in the capillaries in the alveolar walls1 of the left lung.
You notice the erythrocytes around you becoming slightly more red as they absorb
oxygen and release carbon dioxide. You decide to do the same, and soon you have two full
tanks of oxygen. It's a good thing you made it to a lung, as your oxygen supply was
getting dangerously low because your stupid assistant forgot to fill them all
the way when his girlfriend entered the lab. Show off.
1: alveolus n. (pl. alveoli) . . . a
blind-ended air sac of microscopic size. About 30 alveoli open out of each
alveolar duct, which leads from a respiratory bronchiole. The alveolar walls, which
separate alveoli, contain capillaries. The alveoli are lined by a single layer
of *pneumonocytes, which thus form a very thin layer between air
and blood so that exchange of oxygen and carbon dioxide is normally rapid and
complete. . . .
* pneumonocyte n. a type of cell that
lines the walls separating the air sacs . . . in the lungs. Type I pneumonocytes
are flat and inconspicuous. Type II pneumonocytes are cuboidal and secrete **surfactant.
** surfactant n. a wetting agent: a substance,
such as a detergent, that reduces surface tension. A surfactant is secreted by
by the cells (pneumocytes) lining the alveoli of the lungs to prevent the alveolar
walls from sticking together. In its absence, as in the immature lungs of premature
babies and in some diseases, the lungs tend to collapse.
-- The Bantam Medical Dictionary
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