Principles of human physiology / by William B. Carpenter.

  • William Benjamin Carpenter
Date:
1864
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Licence: Public Domain Mark

Credit: Principles of human physiology / by William B. Carpenter. Source: Wellcome Collection.

    103/1026 page 69
    splanclinic, and of the gastric plexuses.* PflUger was led from his obser- vations]* to consider that irritation of the Splanchnic Nerves may, according to circumstances, check the movements of the small intestines if they be already present, or occasion them if the muscles are at rest. 75. From these facts it is evident, that the movements of the Intes- tinal tube may be influenced by the Spinal Cord ; and that what is com- monly termed the Sympathetic nerve, is the channel of that influence, by the fibres which it derives from the Spinal system. But it by no means thence follows, that the ordinary peristaltic actions of the muscles in question are dependent on a stimulus reflected through the spinal cord, rather than on one directly applied to themselves. It is clear that, although these movements are of the first importance to the welfare of the system, such means of sustaining them are feeble, compared to those which we find provided for the maintenance of the distinctly-reflex actions of deglutition, respiration, &c. And the fact that they are capable of being at all times more easily excited by stimuli applied to the muscles, than by any kind of irritation applied to their nerves,—taken in connection with the fact that the muscles not only remain irritable, but will execute regular peristaltic contractions, for a long time after any such contractions can be excited through their nerves,—seems a very strong indication that though the nervous influence is the chief, yet that it is not the only agent in calling these movements into play. And as we well know that the peristaltic movements are affected by particular states of mind, or by con- ditions of the bodily system, the connection just traced satisfactorily ac- counts for this, and is itself sufficiently explained. The rapidity with which the food traverses the intestinal tube is subject to great varia- tions. In a case of artificial anus which opened into the upper part of the jejunum, reported by Dr. Busch,J the first portions of food usually appeared in from 22 to 30 minutes after ingestion. Whilst in another case reported by Dr. Braune,§ in which the artificial anus communicated with the intestine a few inches above the ileo-colic valve; the first appear- ance of the food presented itself three hours after ingestion, and the last about six hours after, so that we may consider the time occupied by the food in traversing the small intestine to be about 2 J hours. The food having tra- versed the small intestine enters the csecum by an aperture guarded by a valve (the Iliocaecal), whose lateral position is clearly a provision for pre- venting the whole weight of the Fseces as the remains of the food here begin to be called by which it might be forced back, from resting upon it. The Fagces in their ascent are lodged in the sacculi of the Colon, by which they are supported during the intervals of the peristaltic action of the Muscular Coat. In their course through the descending colon, they * Budge and Schiff, moreover, in experiments on Cats, obtained intestinal movements on direct irritation of the Corpora Striata, Optic Thalami, Corpora Quadrigemina, Pons Varolii, Medulla Oblongata, and the Peduncles of the Brain and Cerebellum. Longet, however (*' Phys. 1861, vol. i. p. 149), on repeating these experiments in Dogs and Rabbits was unable to arrive at any definite result. See Budge (Lehrbuch der Physiologic, 1862, p. 785), and Schiff, private communication to Longet 'Physiologic, p. 149). Krause is of opinion that the peristaltic movements of the intestines are chiefly the result of the circulation of blood containing a deficiency of oxygen. (See Studien der Physiolog. Instituts zu Breslau, 1863, p. 44.) t Ueber das Hemmungs Nerven System, fur die peristalt. Beweg. der Gedarumen. Berlin, 1856. X Virchow's Archiv, vol. xiv. p. 140. ^ Archives Grenerales de Med., 1861, p. 610.
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