Gastrointestinal motility: regulation and impact on metabolism

Abstract

Abstract. The function of the small intestine is to digest and absorb nutrients. Motility of the small intestine mixes nutrients with digestive enzymes and promotes absorption of the nutrients delivered to the gut. Gastrointestinal motility is organized in motor patterns that are dependent on the nutrient content. In the digestive phase, motility mixes nutrients with intestinal secretions by segmenting stationary contractions. Propulsion is caused by rapid propagated contractions, but also by stationary contractions if there is an aborally decreasing gradient of the number of contractions. Manometry of digestive motility requires closely spaced multiple recording points. In the interdigestive state, the small intestine is swept clear of secretions and debris through the action of the migrating motor complex (MMC) that occurs at variable intervals concomitant with episodes of gallbladder emptying and slowly propagates along the gut. Manometry of MMC is achieved using longer distances between the recording points. Immediately after food intake, nutrients rapidly flow through the intestine; later, digesta accumulates in the distal intestine through the action of inhibitory feedback mechanisms. The slowing of the transit as the nutrients pass down the gut is dependent on the motility pattern evoked in the digestive phase. Disturbance of these motility patterns may have metabolic effects as evidenced by the consequences of a deranged glucose metabolism in diabetes mellitus, in smooth muscle disease with secondary bacterial overgrowth, and in obesity.