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.

  • Combe, Andrew, 1797-1847
Date:
1849
Catalogue details

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.

    56/218 (page 34)
    prive them of active muscular exercise in the open air. In females, the use of tight stays renders the free expan- sion of the chest and corresponding motion of the abdomen altogether im- possible, and thus aggravates the evils of their sedentary mode of life. Hence also the peculiar fitness, in such cases, of the class of purgatives above alluded to, in preference to those of a saline nature, which act chiefly by stimula- ting the mucous surface to farther se- eretion. The mucous, internal, or villous coat of the intestine, also resembles, in many respects, that of the stomach. It isa soft velvety membrane, full of trans- verse wrinkles or folds, called the val- vule conniventes, by means of which the extentof itssurface is greatly increased, so as to afford ample space for the rami- fication of the bioodvessels, nerves, and absorbents, with which it is very plentifully supplied. These folds are large and thickly placed in the duode- num and jejunum, where absorption proceeds with greatest activity. They begin to diminish both in size and closeness of juxtaposition as they ap- proach the ileum, towards the middle of which they altogether disappear. {he surface of the mucous membrane of the small intestines is thickly stud- ded with minute vascular projections, called villi, which vary in length from a quarter of a line to a line and two- thirds, and to which the peculiar velvety appearance is owing. ‘The woodcut on page 33 will convey some idea of the appearance of the mucous membrane, as seen in the smaller in- testines. So far as nutrition is con- cerned it is the truly essential part of the bowel. It alone is in direct con- tact with the chyme, and in its cavity the bile and pancreatic juice perform their respective parts and give rise to the formation of chyle, which is after- wards transmitted from its surface in- to the general system. The peritoneal and muscular coats are useful only in affording protection and communicat- ing the power of propelling its contents. The mucous coat appears, on exami- nation, to be entirely continuous with the skin. In structure the two greatly resemble each other, and an intimate sympathy exists between them. EHrup- frequently owing to disorder of the di- gestive organs; and bowel-complaint, on the other hand, is often produced by a sudden chill on the surface. In like manner, in enormous eaters, like those I shall afterwards mention, an immense exhalation takes place from both the skin and the bowels, and, in many in- stances, the one supplies the place of the other in a considerable degree. In the lowest tribes of animals, moreover, the digesting surfaces and skin are not only undistinguishable, but actually convertible into each other by the sim- ple process of turning the animal in- side out—a clear proof of similarity of both structure and function. mucous coat is charged with the double function of eacreiion and absorption. For the former, it is eminently fitted by its plentiful supply of blood, by the great number of minute vessels ramified on its surface, and by the im- mense number of its follicles. It is by this channel that much of the waste matter requiring to be removed from the body is thrown out. Being poured into the cavity of the intestine it mixes there with the indigestible residuum of the food and bile, and, united with them, forms the feces or excrement. When the blood is suddenly repelled from the surface of the body by a chill, and thrown in upon the mucous mem- brane in large quantity, the natural excretion is sometimes increased to such an extent as to constitute bowel- complaint ; while, at other times, that peculiar form of action is induced which constitutes inflammation. The local stimulus of some kinds of food, and of many medical substances, also ex- cites the secretion to unusual activity. Salts, for instance, have this effect, and thus often produce numerous fluid eva- cuations, the substance or materials of which did not before exist in the bowels; and hence the mistake into which many fall, of taking more medicine, on the ground of this effect proving that much stuff was lodged in the bowels—when,