Please helpe me explain this question. I have searched my textbook and online to try and answer the question: Describe how a complex carbohydrate, a protein, and a fat (triglyceride) are digested and absorbe. The question asks me to include the location and enzymes involved in each step of digestion. Here is what I have so far, but I know there is more to it than these answers. Any help would be greatly appreciated...
Carbohydrate
Digestion begins in the mouth by salivary amylase and completed in the small intestine by pancreatic amylase. Monosaccharides, such as glucose, galactose and fructose, are produced by the breakdown of polysaccharides and are transported to the intestinal epithelium by facilitated diffusion or active transport. Facilitated diffusion moves the sugars to the bloodstream.
Protein
Proteins are broken down to peptide fragments by pepsin in the stomach, and by pancreatic trypsin and chemotrypsin in the small intestine. The fragments are then digested to free amino acids by carboxypeptidase from the pancreas and aminopeptidase from the intestinal epithelium. Free amino acids enter the epithelium by secondary active transport and leave it by facilitated diffusion. Small amounts of intact proteins can enter interstitial fluid by endo- and exocytosis.
Fat
Fat digestion occurs by pancreatic lipase in small intestine. A monoglyceride and two fatty acids are produced in the digestive process. Large lipid droplets are first broken down into smaller droplets, by a process called emulsification. Emulsification is driven by mechanical disruption (by contractile activity of GI tract) and emulsifying agents (amphipathic bile salts). Pancreatic colipase binds the water-soluble lipase to the lipid substrate.
Digested products and bile salts form amphipathic micelles. These micelles keep the insoluble products in soluble aggregates from which small amounts are released and absorbed by epithelial cells via diffusion. Free fatty acids and monoglycerides then recombine into triacylglycerols at the smooth ER, are processed further in the Golgi and enter the interstitial fluid as droplets called chylomicrons, which are then taken up by the lacteals in the intestine.
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