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The honeycomb‐like structure of the bird lung allows an extremely thin blood‐gas barrier
Author(s) -
Watson Rebecca R.,
Fu Zhenxing,
West John B.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a744-b
Subject(s) - lung , capillary action , chemistry , materials science , biophysics , biology , medicine , composite material
Flying requires enormous energy and some birds have higher mass‐specific maximal oxygen comsumptions than any mammal. In keeping with this, the bird lung is very efficient partly because of an extremely thin blood‐gas barrier with the result than some birds have thinner barriers that any mammals. We have found that in addition to the total barrier being very thin, the interstitium which is responsible for the barrier’s strength is extraordinarily thin. This observation is paradoxical because intense exercise raises the pressure in pulmonary capillaries and results in large stresses in the capillary walls thus predisposing them to structural failure. For example, during severe exercise all Thoroughbred racehorses break their pulmonary capillaries and bleed into their lungs. We propose that the explanation for how the bird can be so highly energetic yet also have such apparently fragile capillaries is the mechanical support provided by the dense packing of rigid air capillaries around the blood capillaries in the gas exchanging region of the lung. This architecture is very different from that in the mammalian lung. Supported by NIH 5 R01 HL60968‐06.