Neurophysiologic Mechanisms of Human Large Intestinal Motility

The human colon absorbs water and electrolytes stores feces until elimination is socially convenient, and salvages nutrients by bacterial metabolism of nutrients that were not absorbed in the small intestine. Colonic motility is characterized by patterned contractions of longitudinal and circular muscle layers, which result from interactions between several types of cells in the gut wall (neurons, glia, interstitial cells of Cajal, smooth muscle cells, enteroendocrine cells, resident white blood cells, and fibroblast-like cells) and which are regulated by the extrinsic nervous system. Motility is closely integrated with colonic secretion and absorption. This chapter reviews colonic motility and where possible, relates anatomy, coordinated motor patterns, and propulsion of material to their underlying cellular and molecular mechanisms. Since there are considerable interspecies differences in colonic anatomy and function, the emphasis is on colonic sensorimotor functions in health and disease in humans, supplemented by data from other species, where necessary.