Gastrointestinal Flashcards
Biochemical findings in EPI: B12, folate, TLI, and PLI?
B12: Normal or low (worse prognosis if low)
Folate: Normal or elevated
TLI: Low
PLI: Normal or low
Biochemical findings in pancreatitis: B12, folate, TLI, and PLI?
B12: Normal
Folate: Normal
TLI: Normal or elevated
PLI: Elevated
Biochemical findings in antibiotic responsive diarrhea: B12, folate, TLI, and PLI?
B12: Low or normal
Folate: Normal or elevated
TLI: Normal
PLI: Normal
Biochemical findings in IBD: B12, folate, TLI, and PLI?
B12: Low (if distal S.I. malabsorption)
Folate: Low (if proximal S.I. malabsorption)
TLI: Normal
PLI: Normal
Treatment of Boxer granulomatous colitis?
Enrofloxacin
Ion exchanged for bicarbonate in intestines?
Chloride
Stimulus for acid secretion in stomach?
Acetylcholine (from PSNS), gastrin, histamine
Enzyme responsible for trypsinogen activation?
Enterokinase
Hormone stimulating appetite?
Ghrelin
Major inhibitor of trypsin in acute pancreatitis?
Trypsin inhibitor
Function of Enterochromaffin-like cells?
Secrete histamine to stimulate acid production (stimulated by gastrin)
How are proteins metabolized in the G.I.?
Starts with pepsin in the stomach (10-20%), pancreatic enzymes (trypsin, chymotrypsin, carboxypolypetidase, elastase) split proteins into polypeptides in S.I., carboxypolypeptidase cleaves caroboxyl ends, enterocytes use peptidase enzymes (aminopolypeptidase, dipeptidase) to cleave into tripeptides, dipeptides, and AA’s, further broken down into single AA’s in cytosol of enterocytes
Where is gastrin produced and what is its function?
Secreted by G cells in antrum of stomach, induces histamine release from ECF cells, induces parietal cells directly to secrete acid. Also has functions to increase gastric motility and mucosal hypertrophy
What is responsible for the conversion of pepsinogen to pepsin?
HCl
How does the peptide pump work in the G.I.?
Sodium is actively transported out of the epithelial cells through basolateral membrane. Low intracellular Na pull sodium in through transport protein, which co-transports sodium into the cell (secondary active transport) along with carbohydrate/peptide/AA specific for that transport protein
What is the indication for misoprostol and how does it work?
PGE2 analog, enhances mucosal defense mechanisms and healing in response to acid-related injuries; use for G.I. ulceration secondary to NSAID’s
How does bradykinin effect the blood flow and secretory capacity of the G.I. system?
Causes vasodilation (Increased G.I. bloodflow) and increased secretions
Diagram the flow of bile
Released from the hepatocytes into the bile cananliculi, into terminal bile ducts, hepatic duct, common bile duct. Either empties into the duodenum or is diverted through the cystic duct into the gall bladder
Where is lecithin found and what is it’s function?
Constituent of bile, combines with bile salts and cholesterol to form micelles, keeps cholesterol in solution in the bile
Cisapride MOA?
5-HT4-receptor agonist, enhances release of acetylcholine at the myenteric plexus; increases distal esophageal motility (not dogs due to striated mm), stomach, S.I., and L.I.
PLE test?
Panhypoprteinemia with normal UPC and bile acids; Alpha-1 protease inhibitor is also useful for confirmation of PLE
How do NSAID’s cause G.I. ulceration?
Through inhibition of “friendly prostaglandins” such as PGE2, which serve gastroprotective functions in the G.I.
Explain carbohydrate metabolism in the small intestine
Pancreatic alpha amylase breaks starch down into maltose, other glucose polymers. Enterocytes on brush border contain lactase, sucrase, maltase, and alpha-dextrinase into monosaccharides
What is the protein responsible for iron transport in the small intestine?
Apotransferrin (when unbound to iron) is secreted in bile, binds to iron products in diet (transferrin when bound to iron), pinocytosis into the epithelial cells of S.I.