GI - Digestion, Colon CA, Liver, Gallbladder

gsafsaf's version from 2015-05-27 22:45


Question Answer
Carbohydrate DigestionSalivary + pancreatic amylase --> disaccharides; intestinal brush border enzymes (sucrase, maltase, isomaltase, lactase) --> monosaccharides
Carbohydrate AbsorptionSodium-dependent transport; facilitated diffusion
Protein DigestionPancreatic proteases; trypsinogen--> trypsin, chymotripsin, elastase, carboxypeptidases (secreted as zymogens)
Protein AbsorptionSodium-dependent transport; tri/di-peptides absorb faster than single AAs
Lipid DigestionSalivary lipase + stomach breakdown + pancreatic lipase, colipase, phospholipase 2
Lipid AbsorptionBile salts --> micelles --> TGs + cholesterol --> chylomicron to liver
Iron AbsorptionDuodenum
Folate AbsorptionDuodenum/Jejunum
Vit B12 AbsorptionTerminal ileum (requires IF)

Colorectal cancer

Question Answer
1st step in chromosomal instability APC pathwayLoss of APC gene
2nd step in chromosomal instability APC pathwayK-RAS mutation
3rd step in chromosomal instability APC pathwayLoss of tumor suppressor genes (p53, DCC)
Microsatellite instability pathwayassctd w HNPPCC (Lynch syndrome)
Microsatellite instability pathwayDysfunction of the DNA mismatch repair enzymes
Useful in monitoring recurrence of colon CA, also pancreatic adenocarcinoma markerCEA
FAP3 genetic variants, mutations in APC pathway
Turcot syndromeassctd w FAP, intestinal polyps + Medulloblastoma
Gardner syndromeassctd w FAP, intestinal polyps, bone + soft tissue tumors, lipomas, retinal hyperplasia
HNPCC (Lynch syndrome)AD inheritance, nonpolyposal colorectal cancer; PROXIMAL colon cancer
Hyperplastic polypsNOT considered pre-malignant
Adenomatous polypspre-malignant
Villous adenomasMost malignant of the 3 adenomatous polyps

Liver Pathology

Question Answer
Reye's SyndromeMitochondrial damage --> hepatoencephalopathy
Reye's SyndromeChildhood/rare - aspirin for viral infxn
Hepatic steatosisShort term w/moderate alcohol intake
Alcoholic hepatitisSustained/long-term consumption
Alcoholic hepatitisSwollen/necrotic hepatocytes/neutrophilic infiltration/Mallory bodies (intracytoplasmic eosinophilic inclusions)
Alcoholic cirrhosisSclerosis around central vein
Alcoholic cirrhosisJaundice/hypoalbuminemia
Autoimmune hepatitis Type 1ANA, anti-smooth muscle Ab
Autoimmune hepatitis Type 2anti-liver-kidney microsomal Ab, anti-liver cytosol Ab
Liver pathology/excessive alcohol consumption/biliary tract pathologyElevated Gamma-glutamyl transpeptidase (GGT)
Biliary obstruction/active bone formationElevated alk. phos.
Alcoholic hepatic pathologyAST>ALT (ratio 1.5 usually)
Viral hepatitisALT >/= AST
Hepatocellular carcinoma/hepatomaHBV/HCV/Wilson's/Hemochromatosis/alpha-1-antitrypsin deficiency/cirrhosis/carcinogens such as aflotoxin
Hepatocellular carcinoma/hepatomaJaundice/tender hepatomegaly/ascites/polycythemia/hypoglycemia
Hepatocellular carcinoma/hepatomaIncreased alpha-fetoprotein (AFP)
Cavernous hemangioma30-50
Cavernous hemangiomaBenign
Hepatic adenomaBenign, but can become malignant
Hepatic adenomaOCPs (women 20-40s)/Steroids/Glycogen stoarage diseases
AngiosarcomaMalignant endothelial neoplasm
AngiosarcomaArsenic/vinyl-chlorid (PVC) exposure
Nutmeg liverCHF/Budd-Chiari syndrome backs up blood into liver
Budd-Chiari syndromeIVC/hepatic vein occlusion/centrilobular congestion/necrosis
Budd-Chiari syndromeHepatomegaly/ascites/abdominal pain/liver failure
Budd-Chiari syndromeNO JVD
alpha-1-antitrypsin deficiencyMisfolded protein aggegates in hepatocellular ER
alpha-1-antitrypsin deficiencyPAS positive globules
alpha-1-antitrypsin deficiencyEarly onset panacinar emphysema
alpha-1-antitrypsin deficiencyAutosomal codominant
HemochromatosisDM (iron deposition in pancreas)/Cirrhosis (iron deposition in cirrhosis)/Skin pigmentation (iron deposition in skin) /CHF/Testicular atrophy
HemochromatosisPrimary - autosomal recessive; secondary - excessive transfusions (sickle cell/thalassemias)
HemochromatosisIncreased ferritin; increased total serum iron; increased transferrin saturation; decreased TIBC
HemochromatosisRx: Deferoxamine; phlebotomy

Viral Hepatitis

Question Answer
HAVfecal-oral, 2 wk incubation
HAVDx w anti-HAV IgM Abs
HAVVaccine available
HAVNo chronic or carrier state
HEVNo good Dx test
HEVNo chronic or carrier
HEVNo vaccine available
HEVSevere in pregnant women
HDVIncomplete ssRNA
HDVRequires HBV (HBV vaccine suffices)
HDVsexual, parenteral, transplacental transmission
HCVparenteral > sexual, transplacental
HCVDx w anti-HCV Abs
HCVCarrier + most progress to chronic state
HCVNo vaccine
HCVIncreased risk of HCC
HBVdsDNA virus
HBV60-90 day incubation
HBVsexual, parenteral, transplacental transmission
HBVChronic + carrier states (for the most part only immunocompromised or babies infected transplacentally progress to chronic infxn)
HBVIncreased risk of HCC
HBVVaccine - given before baby leaves hospital in US
+HBsAgActive infxn
+HBsAbNO active infxn [recovered or immunized]
+HBcAbHistory of infxn
+HBcAb IgMacute infxn
+HBcAb IgGchronic infxn or recovered; NOT + after vaccination
+HBeAgActive (acute or chronic) viral replication; high transmissibility
+HBeAbLow transmissibility
HBsAg [timeline]detectible 1-3months post exposure
HBsAg [timeline]no longer detectible after 4-5months post exposure
HBsAb [timeline]becomes detectible about 2 wks after HBsAg goes down
Window periodBoth HBsAg and HBsAb are negative; on the way to recovery

Gallbladder pathology

Question Answer
Primary sclerosing cholangitis (PSC)Concentric fibrosis of bile ducts; ultimate Rx - liver transplant
Primary sclerosing cholangitis (PSC)Strictures + Dilation "beads on string" on ERCP; jaundice, pruritis, dark urine, light stools, elevated alk phos + direct bilirubin
Primary sclerosing cholangitis (PSC)~80% have pANCA; assctd w cholangiocarcinoma
Primary biliary cirrhosis (PBC)Autoimmune disease; T cells attack bile ductules within liver parenchyma
Primary biliary cirrhosis (PBC)Granulomas, jaundice, pruritis, dark urine, light stools, elevated alk phos + direct bilirubin
Primary biliary cirrhosis (PBC)+ antimitochondrial Ab
Primary biliary cirrhosis (PBC)assctd w other autoimmune diseases
Primary biliary cirrhosis (PBC)Rx - Ursodiol - doesn't reverse damage, but slows damage; ultimate Rx - liver transplant
Cholecystitisinflammation/infxn of gallbladder
Cholecystitis+ Murphy's sign
Cholangitisinflammation/infxn of biliary tree
CholangitisCharcot's triad - Jaundice, Fever, RUQ ab pain
Choledocolithiasisgallstones in the bile ducts