Nerve inhibition and its relation to the practice of medicine / by H.O. Thomas.
- Hugh Owen Thomas
- Date:
- [1883]
Licence: Public Domain Mark
Credit: Nerve inhibition and its relation to the practice of medicine / by H.O. Thomas. Source: Wellcome Collection.
20/58 page 14
![H (Part VIII ] is to me explicable only by the supposition that investigators have not made the physiological doses of belladonna the basis for their deduction in prescribing, and its toxic effects their basis for antidotal treatment. If the symptoms which follow the physiological doses of belladonna, are analysed, there always remains evidence of stimulation, and during its action the phenomenon of special affinity for certain structures is demonstrable, just as may be observed during the action of sedatives. Its effect in full physiological doses is to stimulate the radiating fibres of the iris by its special affinity for the sympathetic nerves, a branch of which aids in regulating the radiating muscle of the iris ; but it may be said that this dilatation of the pupil by belladonna arises by the same mode of action as that which causes Henbane to dilate the pupil. But this objection is inconsistent with the fact, that the blood- vessels are diminished in calibre when under the influence of belladonna, from the contraction of their muscular coat (necessarily a stimulative result), so that the pulse is less per- ceptible, but increased in tone, and the temperature becomes elevated. Further, the heart’s action is always accelerated by belladonna from its secondary affinity for and stimulating effect on the vagus nerve, which nerve this drug can protect from the collapse arising from mechanical irritation,* provided the use of the drug be such as not to approach too near the * Foster’s Physiology, page 171.](https://iiif.wellcomecollection.org/image/b28059098_0020.jp2/full/800%2C/0/default.jpg)
