Intestinal and Colonic Chemoreception and Motility

This chapter begins with a review of gastric emptying into the intestine and the intestine’s role in regulating gastric emptying. It then discusses the intrinsic innervation of the small intestine, consisting of the interstitial cells of Cajal, the myenteric plexus, and the submucosal plexus. How these components regulate local responses, including secretion and activity of longitudinal and circular muscles, is discussed. The extrinsic innervation through the sympathetic and parasympathetic nervous system is described. The pattern of motility including segmentation, peristalsis, migrating motor complex or migrating myoelectric complex, and reverse peristalsis is mentioned. Neuronal control of peristalsis is discussed. Motility of the large intestine is then discussed, beginning with its patterns. The various motility reflexes in the gut are then described, including receptive relaxation, gastric accommodation, enterogastric inhibitory reflex; gastrocolic reflex; ileal brake; gastroileal reflex; the various reflexes between ileum and transverse colon; and rectoanal inhibitory reflex. This chapter ends with a description of the neural control of vomiting.