Brazier F, Delcenserie R, Dupas J L
Service d'hépato-gastro-entérologie Hôpital Nord 80054 Amiens.
Rev Prat. 2001 May 15;51(9):945-52.
Hydrolysis of dietary constituents is necessary to allow nutrients absorption by the small intestinal enterocytes. The digestion process takes place in the intestinal lumen, in the brush border membrane, in the enterocyte, and is mediated by a large number of hydrolases secreted in the gastrointestinal tract or produced by the epithelial cells and localized in the brush border. Nutrients are essentially absorbed via a transcellular route across enterocyte cell membranes to enter bloodstream or lymphatic circulation. Transport of nutrients across apical or basolateral membranes occur by active or facilitated mechanisms involving specific transporters. Water, electrolytes and small molecules can be partly absorbed via paracellular pathway. Tight junction permeability is regulated by osmolarity of intercellular space, definite nutrient concentrations in lumen, and activity of brush border membrane transporters.
饮食成分的水解对于小肠肠上皮细胞吸收营养物质是必要的。消化过程发生在肠腔、刷状缘膜和肠上皮细胞中，由胃肠道分泌或由上皮细胞产生并定位于刷状缘的大量水解酶介导。营养物质主要通过跨细胞途径穿过肠上皮细胞膜进入血液或淋巴循环。营养物质通过顶端或基底外侧膜的转运通过涉及特定转运蛋白的主动或易化机制进行。水、电解质和小分子可部分通过细胞旁途径吸收。紧密连接的通透性受细胞间空间的渗透压、肠腔中特定营养物质的浓度以及刷状缘膜转运蛋白的活性调节。
