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Chapter 6.9 Motility of the Gut

BOOK TITLE: Understanding Medical Physiology: A Textbook for Medical Students

Author
1. Bijlani R.L.
ISBN
9788180612213
DOI
10.5005/jp/books/10999_50
Edition
3/e
Publishing Year
2004
Pages
5
Author Affiliations
1. All India Institute of Medical Sciences, New Delhi
Chapter keywords
radiological techniques, gastrointestinal tract, sarcoplasmic reticulum, neurohumoral factors, mixing movements, peristaltic wave, neuronal arrangement, intestinal movements, physiological importance, pressure gradient, defaecation reflex, abdominal pressure, segmental contraction, extrinsic innervation, peristaltic movements, homogeneity

Abstract

This chapter discusses motility of the gut, where two functional types of movements seen in the gut are propulsive and mixing. Smooth muscle of the gastrointestinal tract is made up of long and thin cells which are organised into bundles. The gut has autonomous activity, which is merely modulated by neural factors. The cell membrane of smooth muscle cells is more permeable to ions than is the case with skeletal muscle. The intestine needs a new set of pacemaker cells in every segment because a wave of contraction seldom travels the whole length of the intestine. The small intestine shows both propulsive and mixing types of movements. Intestinal movements are affected by a number of reflexes of physiological importance. Distension of the ileum leads to a decrease in gastric motility. Defaecation reflex is induced by distension of rectum. The major mixing movement of the large intestine is segmentation.

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