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51 Cards in this Set
- Front
- Back
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2 types of digestion?
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1. luminal/cavital (upper tract)
-->enzs from salivary glands, stomach, pancreas 2. membrane/contact (duodenum beyond) |
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enzs for carbs
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salivary glands--> alpha amylase
pancreas--> amylase intestinal mucosa--> -ases for specific sugars |
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enzs for proteins
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stomach-->pepsin
pancreas--> trypsin, chymotrypsin, carboxypeptidase, elastase intestinal mucosa--> amino-oligopeptidase, dipeptidase |
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enzs for lipids
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salivary glands--> lingual lipase
pancreas--> lipase-colipase, phospholipaseA2, CHO esterase |
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enterokinase in intestinal mucosa gives?
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gives trypsin
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total SA of SI?
SI is how long? |
250-400 m2
~20ft, 4-6m |
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folds of Kerckring add how much SA?
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3-fold
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Villi add how much SA?
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10-fold
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microvilli add how much SA?
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1000-fold
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villi allow for ___________ but _________ is a disadvantage
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efficient movement, things can get stuck
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inside each villus is?
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a central lacteal
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epithelial cells of villi...what's the turnover time?
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5 days
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4 mechanisms of absorption
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1. active transport
2. passive diffusion 3. facilitated diffusion (w/ carriers) 4. endocytosis |
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primary active transport is seen where?
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seen on basolateral surface
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secondary active transport is seen where?
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on the luminal surface
(co- and counter-transport) |
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single most impt process in SI to make absorption of nutrients?
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establishment of electrochemical gradient of Na across apical membrane
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ethanol, NSAIDS, aspirin are absorbed where?
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stomach
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what's absorbed at the duodenum & jejunum?
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nutrients, vitamins, various ions, water & electrolytes
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major clinical significance: bile salts & vitamin B12 are absorbed where?
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Ileum
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what's absorbed at the colon?
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water & electrolytes
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drugs such as steroids & salicylates are absorbed where?
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rectum
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synthesis of Vit. K where? by what?
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in large intestine, by bacteria
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to be absorbed by blood or lymph, nutrient must cross how many barriers?
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8 barriers
1. unstirred layer 2. glycocalyx 3. apical cell membrane 4. cytoplasm of enterocyte 5. basolateral cell memb 6. intercellular space 7. BM 8. wall of capillary or lymph vessel |
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starch digestion begins and ends where?
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alpha amylase in saliva (in SI w/ pancreatic amylase) then final at brush border
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w/ alpha amylase in mouth what %, in stomach up to what %?
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5% in mouth
40% in stomach |
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for which 2 sugars, digestion only occurs at brush border?
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lactose & sucrose
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final products of carb digestion are?
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all monosaccharides, mostly glucose
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1 galactose + 1 glucose
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lactose
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1 fructose + 1 glucose
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sucrose
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maltose is all _______
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glucose
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what is the RLS in carb assimilation?
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absorption
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2ndary active transport absorbs which 2 sugars?
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glucose and galactose
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glucose and galactose compete for which membrane carrier?
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SGLUT-1
get energy from Na-K-ATPase |
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fructose is absorbed via what mechanism? thus requires what?
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facilitated diffusion (GLUT-5)
requires con'c gradient, not energy |
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GLUT?? transport hexoses down conc'n gradient via facilitated diffusion
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GLUT2 & GLUT5
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GLUT? transports hexoses against con'c gradient using Na electrochemical gradient via 2ndary active transport
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SGLUT1
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what is the MC abnormality of carb assimilation?
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lactose intolerance
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sxs of lactose intolerance?
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ABD cramps, bloating, diarrhea, & flatulence
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how to dx lactose intolerance?
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feed lactose, look for glucose in plasma
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what do you feed fructose & is dxd at birth?
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lack of glucose/galactose carrier
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digestion of proteins in which 3 locations?
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1. intestinal lumen
2. brush border 3. cytoplasm of mucosal cells |
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from SI, for protein digestion, get?
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endopeptidases, exopeptidases
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enterokinase activates what?
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trypsinogen
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trypsin is___________ and activates other ____________
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autocatalytic
proenzymes |
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in handling proteins, luminal digestion produces % amino acids and % small peptides?
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40% AAs
60% small peptides |
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small (di- & tri- peptides) are absorbed ________ than AAs
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faster!
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see nitrogen in stool?
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when have dec protein absorption w/ pancreatic insufficiency
(pancreatitis or CF) |
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w/ congenital absence of trypsin, get what?
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protein malabsorption
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cannot absorb neutral AAs unless as di- and tri- peptides, what dz?
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Hartnup's dz
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triglyceride to FA 2-monoglyceride happens where?
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duodenum
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FA 2-monoglyceride to triglyceride happens where?
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enterocyte
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