Term
| Main roles of the pancreas |
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Definition
Endocrine pancreas - regulate blood glucose
Exocrine pancreas - secrete digestive enzymes |
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Term
| What are the main cells of the exocrine pancreas |
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Definition
Acinar cells - secrete enzymes & zymogens
Centroacinar cells - secret HCO3- & H2O |
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Term
| Four classes of pancreatic enzymes & what each does |
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Definition
Amylases (digest CHO)
Lipases
Zymogens (digest proteins)
Nucleases/ribonucleases |
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Term
| Fat hydrolysis requires lipase and.... |
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Definition
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Term
| 4 main pancreatic zymogens |
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Definition
pepsinogen
chymotrypsinogen
proelastase
procarboxypeptidase |
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Term
| Zymogens are activated by... |
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Definition
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Term
| What prevents the pancreas from digesting itself? |
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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 |
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Term
| Acinar cell atrophy is an example of a (primary/secondary) pancreatic insufficiency |
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Definition
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Term
| Why is regulation of pancreatic secretion via ACh considered an extrinsic method of control? |
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Definition
| because it's stimulated by the ANS |
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Term
| Secretin promotes the pancreas to release... |
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Definition
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Term
| What creates a negative feedback effect on pancreatic activity |
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Definition
rise in pH of duodenum
digestion & absorption of chyme (lower concentration of nutrients in duodenum) |
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Term
| What circulation supplies the GI tract |
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Definition
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Term
| 3 major arteries of splanchnic circulation |
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Definition
celiac
cranial mesenteric
caudal mesenteric |
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Term
| 75% of blood flow in the GI is to... |
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Definition
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Term
| The GIT receives ___% of cardiac output |
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Definition
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Term
| What increases blood flow to the GI |
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Definition
-most prostaglandings (PGE, PGI)
-tachykinins
-nutrient absorption
-increased metabolic acivity |
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Term
| What decreases blood flow to the GI |
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Definition
-SNS (NE) stimulation (vasoconstriction)
-prostaglandins (PGF) |
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Term
| Most prostaglandins promote GI perfusion. What prostaglandin inhibits it? |
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Definition
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Term
| Why does a reduction in gastric blood flow (e.g. by giving NSAIDS) result in ulcers? |
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Definition
| -surface mucus cells require blood flow to produce alkaline mucus to coat stomach |
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Term
| Signs of mild ischemia in villi |
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Definition
| increased capillary permeability leading to diarrhea |
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Term
| Signs of moderate ischemia in villi |
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Definition
| sloughing of tips/entire villi leading to ulceration & bleedign |
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Term
| Signs of severe ischemia in villi |
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Definition
| Damage to muscular layer of intestine leading to peritonitis, may see intestinal gases in abdomen |
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Term
| Why is decreased blood flow to mucosa significant to intestinal epithelial cells |
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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 |
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Term
True or False
One of the roles of bile is to participate in waste elimination |
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Definition
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Term
| Bile salts are (hydrophilic/hydrophobic) |
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Definition
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Term
| Why do hepatocytes conjugate bile acids? |
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Definition
increases their solubility in water
prevents them from being re-absorbed in the biliary tract & duodenum |
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Term
| Where do horses store bile? |
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Definition
they don't
-continuously secreted into the bile duct |
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Term
| What promotes the gall bladder to release bile acids? |
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Definition
-fat in duodenum stimulates enteroendocrine cells to release CCK
-sphincter of Oddi (gall bladder sphincter) relaxes, gall bladder smooth muscle contracts |
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Term
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Definition
| globules of bile salt molecules which combine with monoglycerides & free fatty acids and then diffuse into the intestinal epithelial cell border |
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Term
| Where are bile salts absorbed? |
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Definition
ileum
NOT duodenum or jejunum |
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Term
| What happens after micelles have 'delivered' monoglyerides & FFA's to the brush border for absorption |
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Definition
| diffuse back into chyme to be re-used |
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Term
| What happens to bile salts that make it to the ileum? |
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Definition
-95% are absorbed via Na+/bile symporter
-some are deconjugated by anaerobic gut bacteria and excreted in the feces |
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Term
| What impact might overgrowth of anaerobic bacteria in the SI have on bile? |
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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 |
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Term
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Definition
| obstruction of bile duct leading to buildup of bile acids in the liver, so some diffuse into the blood |
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Term
| What effect would a loss of functional liver tissue have on bile acids being returned from the gut in portal blood? |
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Definition
| prevents them from being absorbed & recycled, would lead to an increase in serum bile acids |
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Term
| What might cause an increase in bile acids in the blood? |
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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 |
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Term
| Bilirubin is excreted in... |
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Definition
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Term
| Bile secretion by hepatocytes is stimulated by... |
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Definition
-return of bile acids to the liver
-secretin (promotes secretion of H2O and HCO3 which are components of bile) |
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Term
| Bile secretion from gall bladder is stimulated by... |
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Definition
-chyme in duodenum promoting release of cholecystokinin
-vagal simulation |
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