- brush border hydrolases - enterocytes

- no lactase - inc luminal osmolarity--> - net water gain in lumen--> - luminal distension--> peristalsis - diarrhea

export_gi 3 Flashcards by Chelsea Liebowitz

where does digestion occur?

upper part of SI

How well did you know this?

Not at all

Perfectly

intraluminal phase

secrete enzymes

How well did you know this?

Not at all

Perfectly

epithelial phase

brush border hydrolases

- enterocytes

How well did you know this?

Not at all

Perfectly

nutrients absorbed in proximal SI

calcium, fat, AAs, sugar

How well did you know this?

Not at all

Perfectly

nutrients absorbed in middle SI

sugars, AAs

How well did you know this?

Not at all

Perfectly

nutrients absorbed in distal SI

bile salts, vit B12

How well did you know this?

Not at all

Perfectly

3 types of carbs

mono-, di-, polysaccharides

How well did you know this?

Not at all

Perfectly

what types of carbs are absorbed?

mono

- di/poly need to be digested

How well did you know this?

Not at all

Perfectly

enzymes that break down carbs

salivary amylase (mouth), HCl (stomach), pancreatic amylase (SI)

How well did you know this?

Not at all

Perfectly

brush border enzymes for carbs

maltase, isomaltase, sucrase, lactase

How well did you know this?

Not at all

Perfectly

lactose intolerance

no lactase
inc luminal osmolarity–>
net water gain in lumen–>
luminal distension–> peristalsis
diarrhea

How well did you know this?

Not at all

Perfectly

how is glucose absorbed into epithelial cells?

secondary active: Na-glucose cotransporter (SGLT) - apical
facilitated: glucose transporter (GLUT) - basolateral

How well did you know this?

Not at all

Perfectly

transport from interstitial fluid to blood

capillary pores

How well did you know this?

Not at all

Perfectly

protein digestion products

AAs, dipeptides, tripeptides

How well did you know this?

Not at all

Perfectly

what enzymes digest protein?

pepsin, HCl (stomach)
trypsin, chymotrypsin, carboxypeptidase (pancreatic)

-enterokinase, aminopeptidase (brush border)

How well did you know this?

Not at all

Perfectly

what activates pepsinogen

HCl –> pepsin

How well did you know this?

Not at all

Perfectly

what cells secrete pepsinogen?

chief cells

How well did you know this?

Not at all

Perfectly

what cells sectere HCl?

parietal cells

How well did you know this?

Not at all

Perfectly

cascade of enzyme activation of enterokinase…

trypsinogen –> trypsin –> activates other zymogens

How well did you know this?

Not at all

Perfectly

endopeptidase vs exopeptidase

endo- cleaves anywhere in protein

exo- only cleaves terminal amino acid

How well did you know this?

Not at all

Perfectly

how do AAs cross apical membrane?

secondary active, coupled to Na+

- multiple types for diff AAs

How well did you know this?

Not at all

Perfectly

how do AAs cross basolater membrane?

facilitated diffusion

How well did you know this?

Not at all

Perfectly

how are small peptides transported?

secondary active coupled to H+ into cytosol

-broken down to AAs inside

How well did you know this?

Not at all

Perfectly

where is all protein digestion done?

upper SI

How well did you know this?

Not at all

Perfectly

how are full proteins absorbed?

transcytosis- e ndo then exocytosis

what enzyme digests lipids?

lipases

emulsification

break down of fat into droplets -mechanical disturuption -bile salts and phospholipids

what are triglycerides broken into?

monoglyceride + 2 FAs

bile salt fxns

emulsify fat

where and what are bile salts made (from)?

liver, cholesterol

colipase

- amphipathic | - binds water-soluble lipase to fat droplets

what happens once triglys are broken down?

- some absorbed | - micelles

micelles

contain small amounts of fat-soluble vitamins and cholesterol

how are monoglys and FAs absorbed?

simple diffusion

chylomicrons

- tryglys, phospholipids, cholesterol, fat-sol vitamins - secreted by exocytosis into interstitial fluid -enter lymph system and empty in veins in thoracic duct

what happens to FAs and monoglys in epithelial cells?

enter smooth ER and form triglys --> packaged to chylomicrons in golgi

olestra and orlistat

can't be digested by lipases, lipase inhibitor

fat-soluble vitamins

- A,D,E,K - absorbed with lipids -dissolved in droplets, micelles, chylomicrons

water-soluble vits

require diffusion or special transport proteins | -exception: vit B12

vit B12

- absorbed when bound to intrinsic factor | - complex binds to receptors on lumin surface or ilium

what secretes intrinsic factor?

parietal cells in stomach

why do we need vit B12?

-RBC production

causes of low B12?

diet, loss of parietal cells, ileum injury

where is most water absorbed?

80% SI

what drives fluid absorption?

osmotic gradient?

where/how is sodium transported?

active in jejumum, ileum, and colon | -generates osmolarity gradient

how are Cl- and HCO3- absorbed?

passively following Na+

how is iron controlled?

- cellular storage and carrier proteins - control absorption not excretion active transport into intestine epithelial cells

intracellular storage molecule for iron

ferritin (get into cell via DMT1)

what happens to free iron?

in bloodstream in transferrin complex (transport protein linked to ferritin in cells)

what happens to iron-ferritin in epithelial cells?

released back to lumen, excreted

during normal iron stores...

- inc ferritin synth | - dec absorption

during low iron stored

- dec ferritin synth | - inc absorption

hemochromatosis

too much iron absorption --> toxic effects

causes of pancreatitis

- alcohol, drugs, gallstones, genetic mutations - blocked duct - acinar cell injury - defective intracellular transport

symptoms of pancreatitis?

abdominal pain, nausea, vomiting

effects of chronic pancreatitis

- acinar cell loss | - pancreatic fibrosis

causes of liver disease

drugs, toxins, viral, alcohol, metabolic

hepatic failure

- 80-90% liver function lost | - hepatic destruction

symptoms of liver failure

- jaundice - hypoalbuminemia (dec synth of liver cells) -hyperammonemia (inability to clear toxin ammonia products)

acute liver failure

- hepatic necrosis | - induced by dugs/toxins

cirrhosis

- liver cell necrosis, inflammation - hypatocyte dysfunction -due to alcohol, hepatits

export_gi 3 Flashcards

(62 cards)