Hay fever, hay asthma and excessive sneezing / by Litton Forbes.

  • Forbes, Litton.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Hay fever, hay asthma and excessive sneezing / by Litton Forbes. Source: Wellcome Collection.

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    centre, the existence of which is at present somewhat hypothetical, in the medulla oblongata. The practical result is a few rapid inspirations, followed by violent expiration. But in sneezing the air does not pass freely out through the mouth, but by closure of the glottis is forced through the nose. The act is quite involuntary, and can neither be produced at will nor checked. After sneezing, moreover, there is always a discharge of mucus. The nose, which a few moments before the act felt dry, may immediately after it be filled with fluid. The cause of this is due to the fact that two systems of nerves come into play during the act. The cerebro-spinal system conveys the stimulus applied to the nose or skin to the cerebral centre and thence to the throat and expiratory muscles. But this is further supplemented by the action of the great sympathetic, Avhich exercises, among other functions, a controlling influence over the amount of blood sent throusrh the small vessels. The ordinary inhibitory inflaence being for the moment suspended, the highly vascular or erectile tissues in the interior of the nose become ffor^'ed with blood. This produces a temporary swelling or turgidity accompanied by the escape of a large amount of watery fluid. This explanation is, however, not free from difficulties, one being whether the nasal tissues could possibly permit, by mere exudation, the escape of so large an amount of fluid as is generally associated witli the act of sneczini?.