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Digestive 5 & 6
Pancreas, Circulation, Liver
39
Veterinary Medicine
Not Applicable
04/08/2017

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Cards

Term
Main roles of the pancreas
Definition
Endocrine pancreas - regulate blood glucose
Exocrine pancreas - secrete digestive enzymes
Term
What are the main cells of the exocrine pancreas
Definition
Acinar cells - secrete enzymes & zymogens

Centroacinar cells - secret HCO3- & H2O
Term
Four classes of pancreatic enzymes & what each does
Definition
Amylases (digest CHO)
Lipases
Zymogens (digest proteins)
Nucleases/ribonucleases
Term
Fat hydrolysis requires lipase and....
Definition
co-lipase
Term
4 main pancreatic zymogens
Definition
pepsinogen
chymotrypsinogen
proelastase
procarboxypeptidase
Term
Zymogens are activated by...
Definition
trypsin
Term
What prevents the pancreas from digesting itself?
Definition
-secretes enzymes in inactive form (e.g. zymogens)
-releases inhibitor molecules (e.g. trypsin inhibitor) along with the zymogens, which will be diluted in the SI
Term
Acinar cell atrophy is an example of a (primary/secondary) pancreatic insufficiency
Definition
primary
Term
Why is regulation of pancreatic secretion via ACh considered an extrinsic method of control?
Definition
because it's stimulated by the ANS
Term
Secretin promotes the pancreas to release...
Definition
bicarbonate
Term
What creates a negative feedback effect on pancreatic activity
Definition
rise in pH of duodenum
digestion & absorption of chyme (lower concentration of nutrients in duodenum)
Term
What circulation supplies the GI tract
Definition
splanchnic
Term
3 major arteries of splanchnic circulation
Definition
celiac
cranial mesenteric
caudal mesenteric
Term
75% of blood flow in the GI is to...
Definition
mucosa
Term
The GIT receives ___% of cardiac output
Definition
50%
Term
What increases blood flow to the GI
Definition
-most prostaglandings (PGE, PGI)
-tachykinins
-nutrient absorption
-increased metabolic acivity
Term
What decreases blood flow to the GI
Definition
-SNS (NE) stimulation (vasoconstriction)
-prostaglandins (PGF)
Term
Most prostaglandins promote GI perfusion. What prostaglandin inhibits it?
Definition
PGF
Term
Why does a reduction in gastric blood flow (e.g. by giving NSAIDS) result in ulcers?
Definition
-surface mucus cells require blood flow to produce alkaline mucus to coat stomach
Term
Signs of mild ischemia in villi
Definition
increased capillary permeability leading to diarrhea
Term
Signs of moderate ischemia in villi
Definition
sloughing of tips/entire villi leading to ulceration & bleedign
Term
Signs of severe ischemia in villi
Definition
Damage to muscular layer of intestine leading to peritonitis, may see intestinal gases in abdomen
Term
Why is decreased blood flow to mucosa significant to intestinal epithelial cells
Definition
tip of villi somewhat hypoxic even in 'normal' conditions?

countercurrent blood flow -oxygen diffuses from artery to villous veins as you move from base to tip of villi, so the tip is always receiving blood with less oxygen
Term
True or False

One of the roles of bile is to participate in waste elimination
Definition
true
Term
Bile salts are (hydrophilic/hydrophobic)
Definition
both!
Term
Why do hepatocytes conjugate bile acids?
Definition
increases their solubility in water

prevents them from being re-absorbed in the biliary tract & duodenum
Term
Where do horses store bile?
Definition
they don't

-continuously secreted into the bile duct
Term
What promotes the gall bladder to release bile acids?
Definition
-fat in duodenum stimulates enteroendocrine cells to release CCK

-sphincter of Oddi (gall bladder sphincter) relaxes, gall bladder smooth muscle contracts
Term
What are micelles?
Definition
globules of bile salt molecules which combine with monoglycerides & free fatty acids and then diffuse into the intestinal epithelial cell border
Term
Where are bile salts absorbed?
Definition
ileum

NOT duodenum or jejunum
Term
What happens after micelles have 'delivered' monoglyerides & FFA's to the brush border for absorption
Definition
diffuse back into chyme to be re-used
Term
What happens to bile salts that make it to the ileum?
Definition
-95% are absorbed via Na+/bile symporter

-some are deconjugated by anaerobic gut bacteria and excreted in the feces
Term
What impact might overgrowth of anaerobic bacteria in the SI have on bile?
Definition
might deconjugate larger amounts of bile salts than normal, which would move to the colon and promote water secretion into the lumen resulting in diarrhea
Term
What is cholestasis?
Definition
obstruction of bile duct leading to buildup of bile acids in the liver, so some diffuse into the blood
Term
What effect would a loss of functional liver tissue have on bile acids being returned from the gut in portal blood?
Definition
prevents them from being absorbed & recycled, would lead to an increase in serum bile acids
Term
What might cause an increase in bile acids in the blood?
Definition
-loss of functional liver tissue for absorption/recycling of bile acids
-obstruction of bile duct leading to buildup in liver & leakage into bloodstream
-shunt connecting portal circulation & systemic circulation
Term
Bilirubin is excreted in...
Definition
bile
Term
Bile secretion by hepatocytes is stimulated by...
Definition
-return of bile acids to the liver
-secretin (promotes secretion of H2O and HCO3 which are components of bile)
Term
Bile secretion from gall bladder is stimulated by...
Definition
-chyme in duodenum promoting release of cholecystokinin
-vagal simulation
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