Contractile Activity and Control of the Physical Process of Digestion Within a Gut Segment

Abstract

A broad overview is given of the nature and genesis of tonic and phasic contractile activity in the walls of the various segments of the gut, along with an examination of the role of local tension and stretch receptors in regard to the propulsion and mixing of liquid and semisolid digesta. Evidence regarding the control of tonic and phasic contractile activity at a segmental level is reviewed in relation to segmental capacity and to regulating the flow of digesta between the various segments of the gut. The mode of action of the various sphincters and junctions between the component segments of the gastrointestinal tract is then examined with particular attention to the flow dynamics and physical properties of the contents therein. An overview is given of the role of systems that secrete and absorb water in the various segments of the gut which links with more detailed material in Chap. 10.