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24 Cards in this Set
- Front
- Back
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What are the digestible carbohydrates?
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-Starches - amylose, amylopectin
-Glycogen -Disaccharides - sucrose, lactose, trehalose |
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What are the non-digestible carbohydrates?
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cellulose
hemicellulose pectin gums alginate |
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What is oral hydrolysis?
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salivary alpha-amylase begins hydrolysis of starch and glycogen
-action of alpha-amylase is terminated by low pH in stomach |
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What is intestinal hydrolysis?
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pancreatic alpha-amylase hydrolyzes starches and glycogen to oligosaccharides
---alpha-limit dextrins, maltose, maltotriose |
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What are oligosaccharidases and where are they located?
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enzymes that hydrolyze oligosaccharides and disaccharides to monosaccharides
found on brush border (microvilli) of small intestine |
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How do glucose or galactose enter enterocytes (intestinal epithelium)?
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secondary active transport
-enter w/ two Na+ ions Na/K ATPase maintains gradient |
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How does fuctose enter enterocytes?
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facilitated diffusion
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Once inside the cell, how do carbs get to the capillary bed?
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Passive diffusion
carrier-mediated diffusion |
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What causes Lactose intolerance?
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Lactase deficiency (breaks Lactose into galactose and glucose)
---Lactase activity reaches peak levels at birth and drops off w/ decreased milk intake -Autosomal recessive disorder (need two bad genes for phenotype) -increased prevalence in Africans and Asians -decreased prevalence - northern europe Leads to intestinal problems - gas, bloating, diarrhea ---remove lactose from diet |
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What is Lactulose?
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synthetic disaccharide of fructose and galactose
-hydrolyzed in colon, given to pts with liver disease |
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What is a deficiency of sucrase-alpha-dextrinase?
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defect in glucose or galactose transport
-autosomal recessive -remove problematic sugar from diet |
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What are essential Amino Acids (AA)?
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ones that must be supplied from diet
-valine, leucine, isoleucine, lysine, methionine, phenylalanine, tryptophan, threonine -also histidine and arginine in kids |
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Where do we get our essential AAs?
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animal proteins and/or combination of plant proteins if vegan
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What much endogenous proteins are used every day?
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-enzymes, glycoproteins, mucins
--mouth, stomach, intestine, pancreas, biliary tract ~~~20-30grams/day -GI tract epithelial turnover ~~~30 grams/day -Plasma proteins ~~~1-2 grams/ day |
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Protein digestion starts in the stomach. Whats going ON?
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-proteins denatured by acidic pH
-Pepsin hydrolyzes peptide bonds of carboxyl group near aromatic AA residues ---pepsinogen is released by chief cells --> converted to pepsin by low pH -Chyme causes release of pancreatic juices which contain various intestinal endopeptidases and exopeptidases |
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What are the intestinal endopeptidases?
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-Trypsinogen - converted to trypsin by brush border enteropeptidase --> converts other precursor peptidases to active form
-Chymotrypsinogen - active form is chymotrypsin -Proelastase - active form is elastase |
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What are the intestinal exopeptidases?
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procarboxypeptidase A&B
-active form is carboxypeptidases |
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What do endo and exopeptidases do?
What does the brush border do after that? |
hydrolyze proteins to oligopeptides
brush border aminopeptidases hydrolyze oligopeptides to AA |
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How do AA get into intestine cells?
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active, carrier mediated Na+ dependent systems
-similar to galactose and glucose |
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What are the 4 different groups of AAs that require different carriers to get into intestinal cells?
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-neutral AA acids
-basic AA acids -aspartic and glutamic acids -glycine and imino acids (may cause competition for transport sites) |
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What is the ultimate destination of AAs?
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either metabolized or transported to liver
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What is Hartnup's disease?
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defect in neutral AA transport
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What is Cystinuria?
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defect in basic AA and cysteine transport
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Where can you have disorders of digestion of Proteins?
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The small intestine and pancreas
-primary deficiencies are rare -Severity is usually mild |
