The physiology of digestion, considered with relation to the principles of dietetics / [Andrew Combe] ; edited, and adapted to the present state of physiological and chemical science, by James Coxe.

  • Andrew Combe
Date:
1849
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Licence: Public Domain Mark

Credit: The physiology of digestion, considered with relation to the principles of dietetics / [Andrew Combe] ; edited, and adapted to the present state of physiological and chemical science, by James Coxe. Source: Wellcome Collection.

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    The relation between the natural dictates of appetite and the actual wants of the system, is clearly shewn in the uniform increase of appetite consequent on healthy and vigorous exertion. If we indulge in free and active exercise in the open air, and waste by perspiration and exhalation keener, and more urgent for imme- diate gratification; and ifitis indulged after a sufficient interval of repose, we eat with a relish unknown on other occasions, and experience a sensation body were imbued with a feeling of opposite of the restless discomfort and depression which come upon us and ex- tend over the whole system, when ap- petite is disappointed. An amusing example of the principle here incul- cated is to be found in the Correspond- ance Inédite de Madame du Deffand,* where she describes her friend Madame de Pequigni as aninsatiable, bustling, little woman, who consumes two hours every day in devouring her dinner, and “ eats like a wolf.” But then, re- marks Madame du Deffand, by way of explanation, “‘ It is true she takes a fu- rious amount of exercise.” There is, then, an obvious and active sympathy between the condition and bearing of the stomach and those of every part of the animal frame; in virtue of which, hunger is felt very keenly when the general system stands in urgent need of repair, and very moderately when little waste has been suffered. This principle is strikingly illustrated during recovery from a se- vere illness. ‘In convalescence from an acute disease,” as is well remarked by Brachet, “the stomach digests vi- gorously, and yet the individual is al- ways hungry. This happens because all the wasted organs and tissues de- mand the means of repair, and demand them from the stomach, which has the charge of sending them; and, there- fore, they keep up in it the continual sensation of want, which, however, is, in this case, only sympathetic of the state of the body.’* In reference to this subject, Blaine observes, that “Hunger and thirst can only be sa- tisfactorily explained by considering them as properties in the stomach, by which it sympathizes with the wants of the constitution; and hence it is, that food taken in invigorates, even before it can be digested.”t Hence also the prostration of strength that is felt when the stomach has been for some time empty. This sympathy is sometimes singu- larly manifest in disease. Insomecases of affection of the mesenteric glands, for example, where stomachic digestion remains for a time pretty healthy, and the general system suffers chiefly from the want of nourishment caused by obstruction of the passage of the chyle into the blood, the appetite continues as keen and often keener than before. This happens because, the system be- ing in want of nourishment, and the stomach healthy, all the exciting causes of hunger continue to act as before ; and, accordingly, when food is taken, it is digested there as usual, but the chyle which is formed from it in the intestine can no longer be transmitted through theswollen glands in the usual healthy manner, to be converted into nutritive blood in the lungs—and the system thus failing to receive the re- quired supply, recommences its crav- ings almost as if no food had been eaten. When the disease has advanced acertain length, however, fever springs up, and destroys both appetite and di- gestion. The effects of exercise, also, shew very clearly the connection between appetite and the state of the system, If we merely saunter out without be- ing actively enough engaged to cause a waste of tissues and induce increased exhalation from the skin and lungs, scarcely any change of feeling or con- dition ensues; whereas, if we exert ourselves sufficiently to give a general impetus to the circulation, and bring out moderate perspiration, but not to * Recherches Experimentales, &c., p. 181. + Blaine’s Outlines of the Veterinary Art, third edition, p. 273.
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