small intestine | |||
Now back to this aborbtion thing we were talkin' about...
The main carbohydrates present in the small intestine are maltose, sucrose, and lactose, which are absorbed by the microvilli. Starch is broken down into two-glucose units (maltose) elsewhere. The disaccharides are converted into monosaccharides by the enzymes in the cells, which then leave the cell and enter the capillary. If there is a genetic lack of the enzyme lactase produced by the intestinal cells, lactose intolerance will result. Peptide fragments and amino acids cross the epithelial cell membranes by active transport, and inside the cell they are broken into amino acids which then enter the capillary. Digested fats are not very soluble. Fat digestion is usually completed by the time the food reaches the ileum. In the ileum bile salts are absorbed and are recycled by the liver and gall bladder. Fats pass from the epithelial cells to the small lymph vessel that runs through the villus.
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