Mechanism of reflex nervous action in normal respiration / by Austin Flint, jr. ; [phonographically reported by Geo. W. Wells].

  • Flint, Austin, 1836-1915.
Date:
1874
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Licence: Public Domain Mark

Credit: Mechanism of reflex nervous action in normal respiration / by Austin Flint, jr. ; [phonographically reported by Geo. W. Wells]. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the transmission ot the so-called besoin de Tespirev, or sense of want of air, to the respiratory nervous centre. If the pneumo- gastrics were the only nerves which have this function, respira- tion should cease after their division; hut it does not. I do not think that physiologists are at present able to ex- plain the cause of the great diminution in frequency of the respiratory movements, after the division of both pneumogastric nerves ; but this is, nevertheless, an invariable phenomenon. In the experiment to which I have referred, curiously enough, the animal did not die ; and when I presented him to the class, some three weeks after the section of the nerves, the number of respirations had returned to the normal standard. I imagine that a reunion of the two ends of the divided nerve had occurred. A post-mortem examination (the animal being sacrificed in another experiment) showed that the nerves, though not, perhaps, completely united, had formed a partial union, at least, between the divided extremities. The condition of the lungs after the division of the pneu- mogastrics, that is, in cases where death follows such division, is peculiar, and was, for a long time, unexplained by physiolo- gists. In animals that live for three or four days and subse- quently die, the lungs present pretty generally, throughout their entire substance, a carnified condition. They are solid; will sink in water; but still do not present evidences of inflam- mation. It was thought, at first, that this was due to inflam- mation ; but physiologists failed to find the positive evidence of any such action. Bernard, I think, has given the correct explanation of this peculiar appearance. Tie observed tliat, when the respiratory movements are gradually diminished in frequency, they are immensely increased in intensity ; that the inspirations are remarkably prolonged and profound ; and that the chest, in the inspiratory act, is extraordinarily distended. He advanced the idea that this extreme dilatation of the air- cells induced capillary haemorrhage in certain parts of the lungs; that, as this extended, the blood coagulated; and, finally, the lungs became almost solid. Galvanization of both pneumogastrics in the neck arrests the respiratory movements, if it be powerful ; and this action is reflex, not direct. If the nerves be divided, galvanism ot