Volume 1

Human physiology / by Robley Dunglison.

  • Robley Dunglison
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: Human physiology / by Robley Dunglison. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    173/738 page 173
    CHYMIFICATION. 173 tion. On cane sugar a similar effect appears to be induced by admixture with the gastric secretions. It is converted into glucose, wliich when absorbed is more readily appropriated, or a portion of it may be converted into lactic acid. On the whole, in the-present state of our knowledge of this import- ant function, we are perhaps justified in concluding:—First. That by the operation of the gastric secretions the nitrogenized principles of the food, whether animal or vegetable, are dissolved in the stomach. Secondly. That amylaceous matters are converted by the buccal secre- tions into saccharine, and these last are absorbed; or they undergo a farther change, by which they are partly converted into lactic acid, and partly into oleaginous matter [?]. Thirdly. That the oleaginous matters undergo no change in the stomach; and Fourthly. That with the exception of certain mineral substances, matters that cannot be reduced to either of these forms are sent on into the intestinal canal, to be rejected as excrement. In proportion as the food is digested, it passes through the pylorus. After the layer, that lies next to the mucous membrane, has experi- enced the requisite change, and is propelled onwards by the muscular action of the organ, the portion lying next to it becomes subjected to the same process. The gastric fluid, at the same time, penetrates, in a greater or less degree, the entire alimentary mass, so that, when the central portion comes in contact with the surface of the stomach, its conversion is already somewhat advanced. The chyme, thus success- ively formed, does not remain in that organ, until the whole alimentary mass has undergone chymification; but as it is completed, it is trans- mitted, by the peristaltic action, through the pylorus into the duode- num. In the early stages of digestion, the passage of the chyme from the stomach is more slow than in the later. At first, it is more mixed with the undigested portions of food, and, as Dr. Beaumont^ suggests, is probably separated with difficulty by the powers of the stomach. In the more advanced stages, as the whole mass becomes chymified, the process is more rapid, and is accelerated by the peculiar contraction of the stomach, already described. After the expulsion of the last parti- cles of chyme, the organ becomes quiescent, and no more gastric secre- tion takes place, until a fresh supply of food is received, or some me- chanical irritation is produced in its inner coat. The time, required for the complete chymification of a meal, is stated by the generality of physiologists to be about four or five hours. In Dr. Beaumont's case,^ a moderate meal of meat, with bread, &c., was digested in from three hours to three hours and a half We believe that, in by far the majority of cases, a longer time than this is neces- sary ; and in laborioiis digestions, the presence of food can be distin- guished by eructations for more than double the time. It is manifest, that no fixed period can be established for the production of this effect. It must vary, according to the digestive capability of the individual; the state of his general health; and the relative digestibility of the ali- ments employed; all whic:i, as we have already seen, admit of great diversity. It would seem that the most digestible aliments should be
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