A text-book of pharmacology and therapeutics; or, The action of drugs in health and disease : Illustrated with forty-seven engravings.

  • Arthur Robertson Cushny
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of pharmacology and therapeutics; or, The action of drugs in health and disease : Illustrated with forty-seven engravings. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    more highly specialized cells, such as those of the heart, nervous sys- tem, or secretory glands. When stimulation is prolonged or excessive, the protoplasm gener- ally becomes depressed and finally loses its activity entirely (paralysis). Some authorities have asserted that depression is invariably preceded by stimulation, and that stimulation sufficiently prolonged invariably leads to depression and paralysis. Both statements are too absolute, although they are true in the great majority of cases. For example, the action of atropine on the terminations of the cardiac inhibitory nerves is purely depressant. Even the most minute quantities of this alkaloid never increase the activity of these terminations, for if a quan- tity too small to paralyze them is ingested, it has apparently no effects whatever, and as the dose is increased the first effect is paralysis. Depression, whether induced directly, or following on stimulation, has been shown in several instances to resemble the fatigue induced by the prolonged exercise of the normal organ, and it is probably true that depression and fatigue are, in all instances, identical in appearance, al- though not necessarily identical in cause. For example, the phenom- ena of fatigue of the terminations of the motor nerves in muscle re- semble exactly those induced by curara, but in the former the cause may be that the conducting substance of the nerve ends has been used up by the repeated passage of impulses, while in the latter the conduct- ing substance is so changed that it becomes incapable of transmitting stimuli to the muscles. The final result is, of course, the same ; there being no available conducting substance, impulses fail to reach the muscle. But the fatigued terminations rapidly recover, as conducting substance is reformed, while the curarized recover only when the poison is eliminated. In most cases an excessive dose of a stimulating poison leads to de- pression and paralysis. The cell becomes functionally dead, but if the failure of its function does not involve the death of the organism, it may recover and reassume its ordinary function as if no stage of inac- tivity had intervened. Excessive irritation, on the other hand, leads to actual death and disintegration, from which there is no recovery. For example, the cells of the spmal cord are first stimulated, and later paralyzed by a large dose of strychnine, but this is not fatal to cold- blooded animals, and after a few days the spinal cord regains its nor- mal function, as the poison is eliminated. On the other hand, the in- jection of an irritant into the subcutaneous tissues causes dilatation of the vessels, effusion of fluid, and increased growth and rapid division of the cells. If only a small quantity be injected, this condition is re- covered from, although it generally leaves evidence of its presence in the form of an increase in the fibrous tissue. But if the irritation be intense, the cells undergo degeneration and die, and an abscess is formed. The cells thus destroyed can never recover as the paralyzed ones do. They are either absorbed, or removed by the opening of the abscess, and their room is filled by the overgrowth of the neighboring tissues.
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