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15 Cards in this Set
- Front
- Back
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what glands are present in the duodenum that you don't find elsewhere in the gut?
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bruner's glands.
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five major functions of the small intestine:
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propulsion/mixing.
hormone secretion mucous secretion absorption digestion. |
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what four features of the gut increase its surface area?
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cylinder
folds vili microvili (these increase it the most) |
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what are our starches of interest, and what kinds of bonds do they have?
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they're all polymers of GLUCOSE.
amylose has alpha 1,4 amylopectin: A 1-4, A 1-6 glycogen: A 1-4, A 1-6 cellulose: Beta 1-4 (so not digestible) |
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what are our disaccharides of interest? what's interesting about disaccharides and starches?
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first off, we can digest ONLY MONOSACCHARIDES: disaccharides and starches have to be degraded into their respective monosaccharides for digestion.
disaccharides: lactose (glucose and galactose) maltose (glucose and glucose) sucrose (glucose and fructose) trehalose (alpha 1-1, glucose) |
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what are our monosaccharides?
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glucose, galactose, and fructose.
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sugar breakdown - what's the first enzyme that our food encounters that does this, and what are its limitations? what are its products?
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amylase! in saliva.
it's an ENDO-ENZYME: it can't touch the outer sugars or those around the alpha 1-6 linkages present in amylopectin or glycogen. So, it produces lots of maltose, maltotrise, and alpha limit dextrins. |
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so, if amylase can't get the job done, what do we do?
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we need the brush-border hydrolayses: there are a few we need to know.
isomaltase: this is the only guy that can break down alpha 1,6 linkages. sucrase maltase and lactase (note that this is deficient is the majority of the world's population). |
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once we have our monosaccharides, then what happens?
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need transporters to get our sugar into the absorptive enterocytes:
SGLT-1 (sodium glucose co-transporter): works by having an inward Na+ gradient set up by the Na/K pump on the BL side. This transporter works on GLUCOSE and GALACTOSE. Glut-5 transporter gets fructose into the cell. All 3 monosaccharides get out of the cell, into the blood stream, via the Glut-2 transporter on the BL side. |
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in what forms can protein be absorbed into enterocytes? what's nifty about whole protein absorption?
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as either free amino acids or as oligopeptides (2-6 AA's bound together)
absorbing whole proteins doesn't allow for any digestion, but can be useful in immunity building. |
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breakage of peptides into amino acids: where are the majority of peptides forced into their individual AA's?
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mostly intracellularly, by intracellular pepidases.
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what enzymes break down proteins outside the cell, what turns them on, and what do they produce?
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pepsin - from stomach, begins the process.
pancreatic enzymes: trypsin, chymotrypsin, elastase: these are all ENDOpepdidases, so make oligopeptides (all are activated by trypsin, trypsin is activated by enteropeptidase/aka enterokinase). carboxypepdiases from the pancrease are our exopeptidases, make our individual AA's. |
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what's our transporter of proteins into the cell?
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PepT1:
it's a cotransporter of H+ and oligopeptides. these are then broken down by intracellular peptidases into their individual AA's. |
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what's hertnup disease?
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lack of ability to import neutral amino acids, so no tryptophan, means it's harder to make niacin, get deficiency.
other diseases that are interesting include trypsynogen deficiency and cystinuria |
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what's hertnup disease?
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lack of ability to import neutral amino acids, so no tryptophan, means it's harder to make niacin, get deficiency.
other diseases that are interesting include trypsynogen deficiency and cystinuria |
