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18 terms

Module 15A: Chemical Digestion and Absorption

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conversion poysaccharides to disaccharides and finally monosaccharides
Describe the chemical digestion of carbohydrates:
salivary amylase, pancreatic amylase, brush border enzymes lactase
What enzymes are involve in carbohydrate digestion?
mouth, stomach, small intestine
Where does digestion of carbohydrates take place
gastric acid, pepsin, pancreatic juice (trypsin and chymotrypsin), BBE peptidase
What enzymes are involved in the digestion of proteins
gastric acid denatures protein, pepsin protein to peptides and pancreatic juice peptides to amino acids
Function of gastric acid, pepsin, pancreatic juice
stomach, small intestine
Where does digestion of proteins take place
lipids to monoglycerides and fatty acids
Describe chemical digestion of lipids
bile and pancreatic lipase
What enzymes are involved in the digestion of lipids
bile - emulsifies fate; pancreatic lipase breaksdown triglycerides to monoglycerides and fatty acids
Function of bile, pancreatic lipase
mouth, stomach, small intestine (major)
Where does digestion of lipids take place?
pentoses, phosphates, nitrogenous bases
What forms of nucleic acid digestion are absorbed
pancreatic nucleases, brush border enzyme phosphatase
What enzymes are involved in the digestion of nucleic acids
monosaccharides and amino acids are transported across epithelial cells of villi from lumen either through active transport or cotransport with Na+. monosaccharides enter blood capillary of villus by facilitated diffusion, a.a. by diffusion then transported to the liver either to be removed by hepatocytes or will enter general circulation
Describe the route of monosaccharides and amino acids from the lumen of the intestine to the general circulation
bile salts form micelles, where fatty acids and monoglycerides dissolve in the core and the micelles carry fatty acids and monoglycerides to apical surface of epithelial cells of villi for absorption, bile salts are then release absorbed by the ileum and recycled to the liver thru the hepatic portal system; formation of chylomicrons occurs when fatty acids and glycerols in epithelial cells of villus combine to form triglycerides and are coated with protein
Describe the absorption of lipids to include role of bile salts and micelles
fatty acids and glycerols in epithelial cells of villus combine to form triglycerides and are coated with protein
Formation of chylomicrons
chylomicrons leave epithelial cells via exocytosis enter lymphatic lacteals of villi, go to lymphatic vessels, then the thoracic duct, left subclavian vein and finally to general circulation where they are quickly removed by the liver and adipose cell
Route of chylomicrons to general Circulation
vitamin K and B produced by bacterial flora
Name two vitamins produced and absorbed in the large intestine
vitamin B12 combines with intrinsic factor (produced by the parietal cells of the stomach) complex is absorbed via receptor mediated endocytosis in the ileum of the small intestine
Describe the absorption of vitamine B12