Dietary triglyceride digestion

Emulsification/absorption of dietary lipid in the intestine. Bile acids are stored in the gallbladder and released into the duodenum when cholecys-tokinin is released. In the small intestine, bile acids help to solubilise monoglycerides and fatty acids which are formed as the result of the digestion of dietary triglyceride, thereby enhancing the absorption of lipids and the fat-soluble vitamins A, D, E and K. 

Dietary triglycerides, 226, 319-320, 366-367 Digestion, see also AbsorpOon Digestive hormones Digestive molecules Digestive system carbohydrates, 10(3-116 control, 58,88 Cephalic phase, 66-68 chemical phase, 69 innerv ation, 58,66-69 dietary bbers. 143 lipids, 93-103... 

In response to a meal, cholecystokinin is released from the intestine and causes relaxation of the sphincter of Oddi and contraction of the gallbladder (see Chapter 48). This allows a concentrated solution of micelles (consisting of bile salts, lecithin, and cholesterol) to enter the intestine. In the intestinal lumen, dietary cholesterol and the products of triglyceride digestion (predominantly free fatty acids and monoglycerides) are incorporated into mixed micelles. Micelles deliver lipolytic products to the mucosal surface. To carry out these functions, a critical micellar bile acid concentration of 2ramoI/L is necessary. 

Note The role of lingual lipase in the digestion of dietary lipids is minor because it accounts for less than 10% of the enzymatic breakdown of triglycerides. 

An adult ingests about 60 to 150 g of lipids per day, of which more than n nety percent is normally triacylglycerol (formerly called triglyceride). Uhe remainder of the dietary lipids consists primarily of cholesterol, cholesteryl esters, phospholipids, and unesterified ("free") fatty acids. "The digestion of dietary lipids is summarized in Figure 15.2. 

Q9 Lipid in the diet is present mostly in the form of triglycerides, which are digested by pancreatic lipase to yield fatty acids and monoglycerides bile salts are also required for digestion and absorption of the dietary lipids. Bile salts interact with the fatty acids and monoglycerides in the gut lumen to form micelles, which can be absorbed by the epithelial cells. In the epithelial cell the triglyceride is resynthesized to form droplets, or chylomicrons, which enter the lacteals and are carried by the lymphatic system into the general circulation. 

---