Stomach motility pattern

FIGURE 1.3 Pictorial presentation of the typical motility patterns in the fasted (interdigestive) and fed stomach. (From Rubinstein, A., Kin Li, H.K.V., Gruber, P., and Robinson, J.R., in Oral Sustained Release Formulations, Design and Evaluation (A. Yacobi and E. Halperin-Walega, Eds.), Pergamon Press, New York, 1988, p. 125.)... 

Contrary to popular belief, very little drug absorption occurs in the stomach more significantly, it provides a barrier to the delivery and hence absorption of drags by the small intestine. The motility patterns which are responsible for gastric emptying depend on the nature and frequency of food intake and are therefore extremely variable within and between individuals. The stomach is located below the diaphragm, but its exact position varies with the volume of food ingested, posture, skeletal build and the tone of the abdominal muscles... 

Approximately 1 to 1.5 L of fluid is ingested per day, and coupled with secretions from the stomach, pancreas, and proximal duodenum, approximately 8 L of chyme enters the jejunum per day. Reabsorption of 6 to 7 L occurs within the small bowel, leaving a residual of 1.5 L fluid, 90% of which is reabsorbed in the colon. This pattern of liquid reabsorption permits the elimination of fecal waste containing an average of 0.1 to 0.2 L fluid per day. Diarrhea occurs if there is an altered rate of intestinal motility, if mucosal function or permeability is altered, or if the fluid load entering the colon overwhelms colonic reabsorption. Constipation may occur if intestinal movement is inhibited or if there is a fixed obstruction. 

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