Nerve inhibition and its relation to the practice of medicine / by H.O. Thomas.

  • Thomas, Hugh Owen, 1834-1891.
Date:
[1883]
Catalogue details

Licence: Public Domain Mark

Credit: Nerve inhibition and its relation to the practice of medicine / by H.O. Thomas. Source: Wellcome Collection.

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    Do sedatives act as direct stimulants ? I believe they do not; but during their action there may be simulated stimula- tion, and in those instances where this simulation appears, it is during their primary sedative action, — then also the sedative is exerting a minimum or sectional effect only. To illustrate my views, I will discuss the action of opium and alcohol, remedies that properly belong to the class of pure sedatives, and which by their action upon the several organs of the body prove it. Their effects can be best ob- served by noticing their physiological influence upon the iris, heart, blood-vessels, and viscera. If a full dose of opium, short of being a rapidly fatal dose, be given, the diameter of the pupil becomes diminished. This is caused by the drug having a primary sedative or paralysing action upon the radiating muscular fibres of the iris, through its primary affinity for the sympathetic system of nerves specially controlling the radiating muscular fibres. But if a fatal dose be adminis- tered, then the cerebro-spinal nerves, hitherto less affected by by the opium, show signs of its full toxic effect, and the circular muscular fibres of the iris also become paralysed, as evidenced by the increased diameter of the pupil. The effect of opium upon the heart and blood-vessels is to act first upon the blood-vessels, but, secondarily on the heart. Hence we have at first an increased volume in the pulse from diminished tonicity, and finally a slower rate of beat when the dose has been sufficient and has had time to influence the heart. There is also to be observed a diminution of the solid