How motility can enhance mass transfer and absorption in the duodenum: Taking the structure of the villi into account

Abstract

Given the complex motility of the intestinal wall featuring villous structure, the mechanisms by which the motility can enhance mass transfer and absorption in the small intestine have been a mystery. In this work, the challenging task to couple the intestinal lumen flow and the contraction movement of the villi is tackled by a multi-physics model. The effects of motility of an entire duodenum on the mass transfer and absorption under the influence of ambient flow can be systematically explored. It is revealed that the top of the villi plays a major role in mass absorption. For a rat duodenum, the pendular movement can enhance mass transfer and absorption by up to about 72%. With the introduction of ambient flow, although the absorption amount increases, the enhancement of mass transfer by pendular activity is inhibited. Specifically, the average enhancement factor decreases sharply from ~1.35 to ~1.05.