, sucrases, and also lactases, which are also current in the brush border of the little intestinal wall. Maltase breaks dvery own maltose into glucose. Other disaccharides, such as succlimbed and also lactose are broken dvery own by sucrase and lactase, respectively. Sucrase breaks dvery own sucrose (or “table sugar”) right into glucose and fructose, and also lactase breaks dvery own lactose (or “milk sugar”) right into glucose and galactose. The monosaccharides (glucose) for this reason created are took in and also then can be used in metabolic pathmethods to harness power. The monosaccharides are transported throughout the intestinal epithelium right into the bloodstream to be transported to the various cells in the body. The procedures in carbohydprice digestion are summarized in Figure 15.16 and Table 15.5.

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Figure 15.16. Digestion of carbohydprices is percreated by several enzymes. Starch and also glycogen are broken dvery own right into glucose by amylase and also maltase. Succlimbed (table sugar) and also lactose (milk sugar) are broken down by sucrase and lactase, respectively.

A large part of protein digestion takes place in the stomach. The enzyme pepsin plays a critical duty in the digestion of proteins by breaking down the undamaged protein to peptides, which are short chains of 4 to nine amino acids. In the duodenum, various other enzymes— trypsin, elastase, and chymotrypsin—act on the peptides reducing them to smaller sized peptides. Trypsin elastase, carboxypeptidase, and chymotrypsin are produced by the pancreas and released into the duodenum wbelow they act on the chyme. Additional breakdown of peptides to single amino acids is aided by enzymes called peptidases (those that break dvery own peptides). Specifically, carboxypeptidase, dipeptidase, and aminopeptidase play essential roles in reducing the peptides to free amino acids. The amino acids are soaked up into the bloodstream through the small intestines. The actions in protein digestion are summarized in Figure 15.17 and also Table 15.6.

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Figure 15.17Protein digestion is a multistep procedure that begins in the stomach and also proceeds via the intestines.

Lipid digestion starts in the stomach through the aid of lingual lipase and also gastric lipase. However before, the mass of lipid digestion occurs in the tiny intestine as a result of pancreatic lipase. When chyme enters the duodenum, the hormonal responses cause the release of bile, which is produced in the liver and stored in the gallbladder. Bile aids in the digestion of lipids, mainly triglycerides by emulsification. Emulsification is a procedure in which huge lipid globules are broken down into several tiny lipid globules. These small globules are more commonly spread in the chyme fairly than forming big aggreentrances. Lipids are hydrophobic substances: in the presence of water, they will certainly aggregate to create globules to minimize exposure to water. Bile contains bile salts, which are amphipathic, interpretation they contain hydrophobic and also hydrophilic components. Thus, the bile salts hydrophilic side deserve to interconfront with water on one side and the hydrophobic side interencounters via lipids on the various other. By doing so, bile salts emulsify large lipid globules into small lipid globules.

Why is emulsification crucial for digestion of lipids? Pancreatic juices contain enzymes dubbed lipases (enzymes that break dvery own lipids). If the lipid in the chyme aggregateways into big globules, very little surconfront area of the lipids is accessible for the lipases to act on, leaving lipid digestion incomplete. By forming an emulsion, bile salts boost the obtainable surconfront location of the lipids many fold. The pancreatic lipases deserve to then act on the lipids even more properly and digest them, as comprehensive in Figure 15.18. Lipases break dvery own the lipids right into fatty acids and also glycerides. These molecules have the right to pass via the plasma membrane of the cell and enter the epithelial cells of the intestinal lining. The bile salts surround long-chain fatty acids and monoglycerides creating tiny spheres called micelles. The micelles move right into the brush border of the small intestine absorptive cells wbelow the long-chain fatty acids and monoglycerides diffusage out of the micelles into the absorptive cells leaving the micelles behind in the chyme. The long-chain fatty acids and monoglycerides reintegrate in the absorptive cells to create triglycerides, which accumulation right into globules and come to be coated through proteins. These large spheres are referred to as chylomicrons. Chylomicrons contain triglycerides, cholesterol, and also other lipids and have proteins on their surchallenge. The surconfront is additionally written of the hydrophilic phosphate “heads” of phospholipids. With Each Other, they enable the chylomicron to relocate in an aqueous atmosphere without exposing the lipids to water. Chylomicrons leave the absorptive cells using exocytosis. Chylomicrons enter the lymphatic vessels, and also then enter the blood in the subclavian vein.

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Figure 15.18. Lipids are digested and also soaked up in the tiny intestine.

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Figure 15.19. Mechanical and also chemical digestion of food takes location in many steps, beginning in the mouth and finishing in the rectum.