This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
(3) The action of alcohol on the gastric wall produces extensive effects of a reflex kind. The heart is stimulated by moderate doses, producing a pleasurable rise of pressure and sense of power. The vessels dilate universally, filling the active organs with blood, further increasing their activity, the brain being specially excited, and the skin flushed and warmed subjectively. If the quantity be large these salutary effects of alcohol as a diffusible stimulant may pass into depression; and the sudden ingestion of a large amount of spirit may prove rapidly fatal by shock. The reflex results of alcoholic stimulants, if properly applied, add to its value at meal times, by increasing the enjoyment of eating, and thus the digestive power. Certain forms of pain in the stomach and bowels are rapidly relieved by the local action of brandy, which also helps to expel flatus; and pain, spasm, irregular or feeble action of the heart, cold feelings of the surface, and low conditions of the brain are all quickly removed by the same reflex means, before the alcohol could be absorbed in quantity into the blood.
Alcohol enters the blood unchanged, and is distributed by it to the tissues and organs, a small part only becoming lost in it as acetic and carbonic acid. The action of alcohol on the corpuscles is still obscure, but it probably binds the oxygen more firmly to the haemoglobin, so that oxygenation of the tissues occurs less freely, and therefore less extensively. The effect of this upon metabolism will now be described.
Alcohol is rapidly taken up by the various organs, chiefly unchanged. If given in moderate quantity, it is (1) completely oxydised in its passage through the tissues into carbonic acid and water, like other carbohydrates, that is, it is a food, or source of heat and energy. At the same time it produces two other equally important effects; for (2) it reduces the activity of metabolism or the oxydation of the tissues; and (3) it first stimulates, and afterwards depresses, the circulatory and nervous systems, quite independently of its action on tissue-change. These three effects of alcohol must be discussed separately.
(1) Alcohol as a food. - It may now be accepted as proved that, when taken in sufficiently small quantities, alcohol is oxydised in the tissues; and that it only passes out of the body unchanged, through the lungs, kidneys, etc., when so freely given that excretion occurs before oxydation has had time to take place. This decomposition of alcohol must necessarily develop vital force and heat, like the oxydation of sugar, fat, and albumen. Alcohol belongs to the class of foods which do not become an integral part of the living cells, or "tissue proteids," as does much of the albumen, salts, etc., but remain in the plasma which bathes the cells, are oxydised there, and constitute their pabulum, the materials which supply the active elements with much of their energy, the "circulating proteids," carbohydrates, etc. Thus it happens that alcohol can for a time sustain life when no food (so-called) is taken, as in confirmed drunkards, and in some cases of severe illness. Professor Binz, of Bonn, who has studied this question with great industry and success, has calculated how much energy is contained in a gramme of alcohol, and finds that two ounces of absolute alcohol yield about the same amount of warmth to the body as is supplied by an ounce and a half of cod-liver oil. The uses of alcohol as a food will be presently described along with its other applications.
(2) Alcohol as a nutritive depressant. - Whilst it is itself thus oxydised in the tissues, alcohol unquestionably interferes with the metabolism or oxydation of other substances, especially (it would appear) saving or sparing the wear and tear of the "tissue-proteids," or formed protoplasm of the cells. This has been determined from three facts observed in animals supplied with alcohol; first, that less oxygen is absorbed; secondly, that the temperature falls, and the albuminous tissues, whilst they do not waste, tend to degenerate into fat, so that the body as a whole grows fat and gross; thirdly, and chiefly, that the amount of urea, uric acid, carbonic acid, and salts excreted, is decidedly diminished. These are settled fac ts; the explanation of them is more difficult. The interference of alcohol with the oxygenating function of the red corpuscle is one obvious cause of impaired metabolism; another is the extreme readiness of the alcohol when it reaches the tissues to seize upon the oxygen which is there, thus robbing as it were the fixed elements of their necessary share, and arresting their decomposition at the middle stage of fat. This remarkable property of alcohol of saving tissue waste is one of the foundations of its employment in fever, to be presently discussed.
(3) Alcohol as a stimulant and narcotic. - The circulation in every part of the body is stimulated by a moderate dose of alcohol. The rise in the force and frequency of the heart, and the dilatation of the peripheral blood-vessels, which together constitute this increased circulatory activity, are both so far reflex effects from the mucous membrane of the stomach, as we have already seen; but they are also in part direct, the alcohol exciting the nervo-muscular structures of the heart, the cardiac centre, possibly the vaso-dilator centres in the medulla and cord, and certainly the nervo-muscular tissue of the middle coat of the vessels. To these causes of circulatory excitement must be added the voluntary muscular movements which are much exaggerated under the influence of alcohol. When alcohol is taken in large quantities, its stimulant effect passes into depression, both reflex and direct, and death may result, in part at least from cardiac failure.
Upon the nervous system, the first effect of alcohol in moderah quantity is one of stimulation. The nervous centres are increased in vigour from the highest to the lowest, and in the same order of sequence. The imagination becomes brilliant, the feelings are exalted, the intellect is cleared, the will is strengthened, the senses become more acute, the leafing of bodily strength and ability is raised, and some of the appetitef are temporarily excited. The centres of speech, and of muscu-lar movements generally, are specially exalted, giving rise to animated talk and lively gesticulations; and. therewith, a sense of bien etre, referable to the combined nervous and circulatory excitement, spreads over the system.