Absorption

What is celiac spruce

Dierary gluten triggers T-cell mediated autoimmune destruction of small bowel vili

What does celiac spruce lead to

malabsorption of fat, fat-soluble vitamines, iron, and folate

Blood test for celiac spruce

blood test for antibodies + biopsy

Where is most water reabsorbed

small intestine

Ulcerative colotis location

colon

Lesions on ulcerative colitis

continuous

How does ulcerative colitis look

Crypt distortion; pseudo-polyps

What does ulcerative colitis lead to

loss of haustra

What does ulcerative colitis do to the colon as a whole?

megacolon

Where is crohn’s disease

any GI segment

What kind of lesions crohn’s disease

skip leasions

What kind of ulcers crohn’s disease

deep + fissures

What happens to wall in crohn’s disease

thickened wall, fat wrapping, and cobble-stoning

What can crohn’s disease cause in ileum

B12 and bile acid malabsorption

How does Na enter the apical membrane

Cotransport with nutrients, Na/Cl symporter, Na/H+ exchanger

How does Na enter basolaterally?

Na-K-ATPase

How does Cl enter apically

Na/Cl symporter, Cl/HCO3 exchanger

How is Cl absorbed basolaterally

Paracellular route, Cl' channels

How does water follow NaCl

aquaportin channels

How are vitamin B and C transported?

Carrier mediate membrane transporter

How does Na enter in large intestine

ENaC

What does ENaC result in

net secretion of K+

What regulates ENaC

aldosterone

How is Cl secreted

CFTR channel

What regulates the CFTR channel for Cl sec

cAMP

What does basolateral NKCC1 do

brings Cl into cell with K and Na

What increases Cl channel activity

VIP, ACh, Serotonin

What does PDE4 do

breaks down cAMP

What does PDE4 cause

less Cl secretion into lumen

What does Na follow

Cl

What does water follow

Na

What does Cl movement indirectly cause

water mvmt out of cell

What is secretory diarrhea

Excess chloride secretion

Sign of secretory diharrhea

diarrhea without eating

What is osmotic diarrhea

Stops with fasting

What dies cholera and ETEC heat-labile toxin do?

Increases cAMP

What does CFTR cause with stool?

Less Cl, so thick secretion (intestinal obstruction risk)

What is a VIPoma

Increased VIP

What can VIPoma cause

WDHA

Results of VIPoma in body

watery diarrhea, hypokalemia, achlorhydia

What regulates Ca transport

PTH and Calcitriol

What stimulates PTH

low Ca

What gets stimulated by PTH

renal 1a hydroxylase

What does renal 1a hydeoxylase icnrease

1, 25 OH

What does calcitriol increase

duodenal transcellular Ca2+ absorption

What absorbes Ca2+ more via calcitriol

TRPV6, Calbindin, PMCA

What does TRPV6 do

increased apical Ca

What does calbindin do?

Prevents Ca from leaking out of cell

What do basolateral Ca extrusion do?

Ca released

What does vitamin D cause

osteomalacia, rickets, decreased plasma Ca and increased PTH

Inhibitors of Ca absorption

oxalates, phytates

What contains ocalates

spinach, rhubarb

What does decreased liver ferritin do

decreases hepcidin

What does decreased hepcidin cause

increased ferroportin

What does increased ferroportin cause

increased Fe in bloodstream

What does Fe bind to

transferrin

What deos Fe do once it binds to transferrin

Stored as liver ferritin

What does increased liver ferratin stores do

increases hepcidin

What increases due to liver ferritin stores

hepcidin

What does high hepcidin do

decreases ferroprotin

What does decreased ferroportin cause

decreased Fe in bloodstream

What does low Fe in bloodstream cause

transferrin is bound iron is transported to liver

What carries heme

HCP1

What brings heme in from the lumen?

heme oxygenase

What brings non heme iron in?

Endosome

How is Fe3+ reduced to Fe2+

Gastric acid uses 1 DCT1, which puts more Fe in enterocyre

What dies Fe inside the enterocyte use to enter the bloodstream

ferroportin

What is hemochrmoatosis

Mutation in hepcidin

what does the C282Y mutation cause

decreased hepcidin, increased ferroportin

What dies high serum iron, ferritin and transferrin look like?

Hemochromatosis

How C282Y inhereted

recessivly

Where are iron and calcium taken in

Duodenum and jejunum

What does B12 bind in the stomach and saliva

Haprocorrin

What does haptocorrin do

protects B12

What can digest haptocorrin

Pancreatic proteases

What does B12 bind after haptocorrin

Intrinsic factor

What does B12 bind in blood

transcobalamin

What does B12 deficiency cause

megaloblastic anemia

What does B12 cause in brain

memory loss, confusion, difficulty concentrating

Labs for b12 deficiency

Increased MMA, homocysteine

Symptom of folate deficieency

Inc homocyteine only

Sites of digestion: Luminal

Saliva, gastric acid, pancreatic enzymes, galbladder

site of digestion: membrane

Enzymes on the brush border

Cutoplasmic digestion

proteolytic enzymes

When is the absorption of macronutrients more uniform?

when there are macronutrients, rather than iron/ca/bile/b12

Where does digestion of carbohydrates begin

in the mouth

What does CCK stimulate for carbs

pancreatic amylase

What does the brush border have for carbs

maltase, sucrase, isomaltose, oligosaccharides, lactase

What does maltase do

Makes 2 glucose

What does sucrase do

makes glucose and fructose

What does isomaltose do

Oligosaccharides → shorter glucose polymers

What does lactose do

glucose to galactase

Transporters for Carbs

Apical SGLT1, GLUTs, GLUT2

What does SGLT1 do

glucose and galactose uptake with Na

What does apical glut5 do

fructose uptake, basolateral

what does glut 2 do

exports glucose, galactose, and fructose to blood

what does lactase deficiency cause

milk intolorance, bloatic, osmotic diarrhea

What does glucose-galactose malabsorption syndrome do

bloating and osmotic diarrhea

What is mutated in glucose-galactose malabsorption syndrome

SGLT1 mutation