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30 Cards in this Set
- Front
- Back
types of proteins that can be absorbed in SI
|
di, tri & tetra peptides
aa's |
|
where does protein digestion begin
|
in duodenum with enteropeptidase conversion of trypsinogen to trypsin
|
|
pancreatic peptidases
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trypsin
chymotrypsin elastase carboxypeptidase A & B |
|
activation of trypsin
|
secreted by pancreas as trypsinogen
activated by enteropeptidase on brush border |
|
characteristics of enteropeptidase
|
membrane bound
on brush border of SI serine protease (NOT kinase) |
|
"layers" of peptidases
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1st layer
trypsin chymotrypsin elastase carboxypeptidase A & B 2nd layer in cytoplasm "cytoplasmic peptidase" |
|
digestion of proteins
|
begins in small intestine
trypsinogen activated by enteropeptidase trypsin activates other peptidases cut into di, tri & tetras transported into cytoplasm cytoplasmic peptidase specific aa transporters at basolateral membrane |
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peptide transporter into enterocyte
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Na/K pump at bl memb drives Na out
draws Na in at apical aa's cotransport PepT1- peptides & H+ in |
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inability to absorb neutral aa's from SI lumen
(need tryptophan to make niacin so get niacin def) symptoms include dermatitis exacerbated by sunlight |
Hartnup disease
|
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aa transporter with 2 subunits
impaired cationic aa transporter liver & kidney problems sx of malnutrition |
cystein (def is cysteinuria)
|
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maple syrup urine disease
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leucin, isoleucine, valine
|
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absorption of carbohydrates
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begins in mouth with alpha amylase (amylose, amylopectin)
hydrolyzed to monosaccharides SGLT 1 brings glucose & galactose in from lumen GLUT 5 brings in fructose transported out of enterocyte by GLUT 2 |
|
maltose
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2 glucose (alpha 1-4 link)
|
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maltotriose
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3 glucose (alpha 1-4 links)
|
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alpha dextrins
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short oligosaccharides
|
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lactose
|
glucose & galactose
|
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sucrose
|
glucose & fructose
|
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trehalose
|
glucose
|
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SGLT 1 transporter
|
Na/K pump at BL membrane (Na out)
SGLT at apex glucose or galactose and 2 Na come in |
|
GLUT 5 transporter
|
fructose in
facilitated diffusion |
|
protein disorders
|
Cysteinuria/lysinuria
Maple Syrup Disease Hartnup disease |
|
Carbohydrate disorders
|
GGM
Sucrase Isomaltase Deficiency Lactase deficiency Hypolactasia Celiac Sprue |
|
severe watery diarrhea in infant
resolved if on fructose diet |
GGM- glucose/galactose malabsorption
mutation in gene encoding SGLT 1 |
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characteristics of SGLT 1 transporter
|
14 membrane spanning domains
Glycoprotein (subjected to post transcriptional modification- glycosylation activates or inactivates) |
|
Severe watery diarrhea at about 3 months
resolved with galactose only |
Sucrase/Isomaltase Deficiency
(glucose & fructose not absorbed) |
|
diarrhea
releived with removal of lactose |
lactase deficiency
|
|
hypolactasia
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lactose intolerance
starts around 2-5 years recent mutation allows N Europeans to drink milk |
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detection of lactose intolerance
|
lactose tolerance test
stool acidity test Breath hydrogen test |
|
flattening of lining of SI
poor absorption of nutrients |
Celiac Sprue
autoimmune rxn to gluten 1/133 in US |
|
mechanism of diarrhea in carb absorption dz
|
osmotic
b/c Na & H2O not able to come in |