Principles of human physiology / by William B. Carpenter.

  • William Benjamin Carpenter
Date:
1864
Catalogue details

Licence: Public Domain Mark

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

    98/1026 page 64
    (the Dog, for example), section of the pneumogastric does not produce that check to the propulsion of the food, which it occasions in the Rabbit; and even in the Eabbit, as Dr. M. Hall has remarked,* the simple con- tractility of the muscular fibre occasions a distinct peristaltic movement along the tube, after its nerves have been divided; causing it to discharge its contents when cut across. Such a movement, indeed, seems to take place in something of a rhythmical manner (that is, at short and tolerably regular intervals,) whilst a meal is being swallowed; but as the stomach becomes full, the intervals are longer, and the wave-like contractions less frequent. The reopening of the cardiac orifice, on pressure from within (which is usually resisted by the sphincter, as in the acts of defecation, par- turition, &c.), is one of the first of that series of reversed actions which con- stitutes the act of Vomiting; and this is accompanied by a reversed peristaltic action of the oesophagus. The independence of these actions, one of another, and their relation to a common cause, is remarkably shown by the fact, that when vomiting takes place as a consequence of the injection of tartar-emetic into the veins, the reversed peristaltic action of the oesophagus is performed even after its separation from the stomach. 71. The food, which, thus propelled along the oesophagus, enters the Stomach through its cardiac orifice in successive waves, is immediately subjected to a peculiar peristaltic movement, which has for its object to produce the thorough intermixture of the gastric fluid with the alimentary mass, and to separate the portion which has been sufficiently reduced, from the remainder. The fasciculi composing the muscular wall of the Human stomach, are so disposed as to lessen its diameter in every direc- tion ; and whilst the cavity is empty, they are uniformly contracted, so as to reduce the organ to its smallest dimensions. When food is introduced, the contraction of the parietes as a whole still continues, to such a degree as to make them closely apply themselves to its surface ; but the contraction of the individual fasciculi alternates with relaxation, in such a manner as to induce a great variety of motions in this organ, sometimes transversely, and at other times longitudinally. These motions, remarks Dr. Beau- mont, who has enjoyed a peculiar opportunity of observing them,*]* not only produce a constant disturbance or churning of the contents of the stomach, but they compel them at the same time to revolve about the interior from point to point, and from one extremity to the other. In addition to these movements, there is a constant agitation of the stomach, produced by the respiratory muscles. The nature of these, and indeed of all peristaltic movements, has been stated by Dr. Brinton \ to resemble very closely those produced by the descent of a perforated piston in a closed tube containing fluid, for here there would be peripheral currents passing in the same direction as the piston, and a central current flowing in the opposite direction, through the perforation in the piston. The direction which the particles of food take, as described by Dr. Beau- mont, corresponds very fairly with this view. He says:— The bolus as * Third Memoir on the Nervous System, § 201. + See the Case of Alexis St. Martin, with Observations and Experiments by Dr. Beaumont, republished in this country by Dr. Andrew Combe.—This patient had a large fistulous orifice in his stomach, remaining after a wound which had laid-open the cavity ; but his general health had been completely restored. X *'Cyclop. Anat. and Phys., vol. v. pp. 313 and 345.
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