They introduced some new nomenclatures while describing them However,

the movements of human srnall intestine. They introduced some new nomenclatures while describing them However, on the whole The movements are basically simlar to Those found by the earlier workers on the animals. THE MOVEMENTS Description and utility. (i) Segmentation or segmenting contractions were described by Cannon. In this movement, constrictions appear at several points in a portion of The intestine Therefore, that portion of the intestine is divided into several segments, each bounded by a ring of constriction on either side. Each segment is about 1 or 2cm long. Very soon a constriction ring appears in the middle of each segment but The previous constrictions now disappear. This process is repeated (fig.3.7.3) and the constriction rings again appear at the sites where they appeared first. Fig. 3.7-3 Segmenting movement Segmenting contracticns obviously, results in mixing of the food matter (chyme) with juices available in the intestine (like pancreatic juice and bile). This type of contractions can not cause propulsion of the chyme in the aboral direction. (ii) Pendular movements are similar to The segmenting contractions: however the individual segments formed are large, about 20 cm in length Therefore, the chyme moves forward i.e. in the aboral direction hist and then retraces its path next. This type of movement helps the liquid chyme (recall. That the chyme delivered from the stomach is either liquid or nearly so) to move to and fro. like the pendulum of a wall clock, i.e. it is exposed to a large area of intestinal mucosa provided by the villi and microvilli. The intestine acts here as a powerful shaker, (iii) Peristaltic waves, first described by Starting and Bayliss. consist of a ring of contraction which moves forwards, i.e. in the aboral direction. The result is that the chyme moves in the forward, i.e. aboral. direction So peristalsis is a propulsive movement. Because of the fact That it sleeps onwards, it is also spoken of as a translatory movement. Starling and Bayliss
visualized the whole process as follows . a sort of a mass of chyme appears somewhere in the small intestine and acts as a stimulus (stretching produced by The bolus is actually the specific stimulus). As a result the ring of constriction appears behind (i.e. cranial to ) the mass and relaxation occurs in front (i.e. caudal to) of the mass and the mass therefore moves forward. In its fresh. i.e. new position. The mass again acts as a stimulus and the whole process is repealed. This conception remains valid till to dates. Peristalsis waves are superimposed on segmental movements. [NB. According to