Gastro

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docdee
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174977
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Gastro
Updated:
2012-10-07 19:05:06
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usmlemix
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GI
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  1. Stomach stretch makes what two things?
    • 1. Ach - gastrin - makes acid.
    • 2. Prostaglandins that make mucus

    Both are protective for the stomach
  2. Unique features about saliva.
    • Stimulated by SNS and PNS (SNS makes thick secretions and PNS makes increased volume)
    • Has a Cl-pump in the acinus
    • Hypotonic so we can taste food
    • Amylase but not essential like pancreatic lipase
    • No protein digestion enzymes (therefore, tofu tastes like nothing)
  3. Diphenoxylate for diarrhea?
    Opiod agonist that binds to mu receptors in GI tract and slows motility. High doses combined with atropine to decrease physical dependance and euphoria
  4. Secretory diarrhea treatment?
    Bismuth sulfate and ocreotide
  5. Urease test
    • Urea is converted to CO2 and NH3 and causes a pH increase - causing alkalinization of the urine.
    • CO2 measured in a breath test.
  6. Bilous vomiting in 24 hours due to intestinal obstruction after the duodenum. MoA?
    Intestinal stenosis and atresia: absence of part of the bowel (e.g. formation of blind-ending proximal jejunem) and terminal ileum wraps around an ileocolic vessel.
  7. Base excision repair (e.g. xeroderma pigmentosum) cytosine deamination creates unusal uracil binding. Steps to repair it? 
    • Glycosylase cleaves the misplaced uracil
    • Endonuclease cleaves the 5' end and lyase cleaves the 3' end
    • DNA polymerase and ligase fill in the single nt gaps
  8. Colonic diverticula: MoA?
    • Increased intraluminal pressure causes mucosa and submucosa to herniate through weak spots in the muscular layer.
    • sigmoid colon
    • Risk factor: chronic constipation
  9. Pancreatitis due to alcohol or gallstones with pancreatic exocrine insufficiency lead to?
    Malabsorption (fatty stools) due to failure to secrete adequate amylases, proteases, lipases. 
  10. Sx of gallstones obstructed in the cystic or common bile duct? 
    Biliary colic, jaaundice, cholangitis: fever, RUQ pain, + Murphy's sign. 
  11. Long history of gallstones and now shows air in the gallbladder and biliary tree. Where is the stone?
    Gallstone ileus: Cholecystenteric fistula forms --> allows stone to go into the small bowel and dislodge in the ileum. Intestinal gas enters the gallbladder and biliary tree. 
  12. Vessels of the retroperitoneum?
    AA, IVC
  13. Solid organs of the retroperitoneum?
    Pancreas (except the tail), kidneys, adrenal glands
  14. Hollow organs of the retroperitoneum?
    2nd and 3rd part of the duodenum, ascending and descending colon, rectum, ureters, bladder
  15. Lactase administration to lactose intolerant patients. Lab values?
    • Increased osmotic stool gap (osmolarity increases due to decreased absorption of substances)
    • Increased breath H+ content (osmotic diarrhea)
    • Decreased stool pH
  16. Prevalence of a disease directly and indirectly depends on what factors? 
    • PPV
    • NPV (inverse relationship with prevalence)
  17. Imperforated anus 
    • Abnormal development of anorectal structures (small dimpling instead of an anus opening)
    • Inability to pass meconium
    • Meconium can exit from urethra if fistula present = GU problems
    • Associations: VACTERL (less common than GU sx)
    • vertebral defects
    • anal atresia
    • cardiac problems
    • TE fistula
    • esophageal atresia
    • renal problems
    • limb defects
  18. Systemic sclerosis pathogenesis? 
    CD4 accumulation, increased tissue fibrosis due to collagen deposition
  19. What does Campylobacter show on a stool test?
    • Absence of ova and parasites
    • Inflammatory: watery and then bloody
  20. Toxins of C.difficile.
    • Toxin A (enterotoxin): mucosal inflammation, loss of water with diarrhea, mucosal death
    • Toxin B (cytotoxin): actin depolymerization, loss of cytoskeleton integrity, mucosal necrosis
  21. Which drugs cause mitochondrial toxicity?
    • 1. NRTIs
    • 2. cyanide
  22. Crohn's dz and gallstones relationship? 
    • Normal: bile acids are produced in liver, excreted with bile and reach terminal ileum become micelles with fat and reabsorbed in the liver again. 
    • Crohn's: damaged terminal ileum - no bile acid reabsorption = gallstones
  23. Arsenic poisoning (garlic odor on breath) treatment?
    Dimercaprol
  24. Which antibody level will differ 1 month after giving a live and a killed vaccine?
    Mucosal IgA (immune protection)
  25. Adverse effects of protease inhibitors
    • Hyperglycemia
    • Cushing's (lipodystrophy = redistribution of fat)
    • P450 inhibition
  26. Which Hep viruses are mostly anicteric?
    Hep A and E (fecal-oral)
  27. How does Giardia cause injury? 
    Injury to the duodenal and jejunal mucosa by adhering to the intestinal brush border, severe IgA deficiency predisposes (no adaptive immunity)
  28. Penetrating injuries to the abdomen cause abscesses of what bacteria?
    Mixed aerobic and anaerobic bacteria
  29. Histo of acute viral hepatitis?
    • Ballooning degeneration (hepatocyte swelling)
    • Councilman bodies (eosinophilic apoptotic hepatocytes)
    • Hep A and E
  30. Histo of chronic viral hepatitis? 
    • Nodular regeneration
    • Hep B and C
  31. Mechanism of esophageal varices?
    Increased venous pressure associated with cirrhosis
  32. Mechanism of Mallory-Weiss syndrome?
    • Increased intraluminal/abdominal pressure caused by vomiting, retching. 
    • Hiatal hernias also a cause
  33. Mechanism of cirrhosis-related hepatic encephalopathy
    Treatment
    • Increases NH3 deposition due to waste products (GI bleeding, hypovolemia, hypokalemia, metabolic alkalosis, infection, hypoglycemia)
    • Lactulose
  34. Mechanism of Zenker's diverticulum?
    • Cricopharyngeal muscle dysfunction (decreased relaxation of pharyngeal muscles during swallowing). 
    • Increased intraluminal pressure causes mucosa to herniate through
  35. Southwestern blot: substance and probe? 
    • DNA binding proteins (c-jun and c-fos)
    • dsDNA probe
  36. Ras
    • Proto-oncogene: codes for a membrane-G protein which activates MAP kinase pathway and activates transcription.
    • Doesnt directly bind to DNA
  37. Processes that occur in the mitochondria
    • 1. Glycolysis/Gluconeogenesis
    • 2. B-oxidation
    • 3. TCA
    • 4. Urea cycle (OTC)
  38. Which cells cannot use ketone bodies?
    • 1. RBCs have no mitochondria
    • 2. Hepatocytes have mitochondria, but lack succinyl-coA enzyme
  39. Inactivating Hep A virus mechanisms
    • 1. irradiation
    • 2. water chlorination
    • 3. boiling for 1 min
    • 4. bleach
    • 5. autoclaving (120C) for 20 mins
  40. Bioavailability of drug by IV route
  41. Bioavailability of drug by oral, IM or other route besides IV
    • <1
    • Area under oral curve x IV dose/Area under IV curve x oral dose
  42. Gallbladder stones during pregnancy or use of OCP
    • 1. Estrogen upregulates HMG-CoA reductase increasing cholestrol synthesis
    • 2. Progesterone-induced gallbladder hypomotility and decreases bile secretion
  43. Gallbladder hypomotility causes what stones?
    Biliary stones (decrease in bile reabsorption)
  44. Cephalic phase
    • Cholinergic and vagal stimulation
    • Presence of thought, sight, smell, food
  45. Gastric phase
    Gastrin stimulation and stomach distention increases acid release
  46. Intestinal phase 
    • Inhibits gastrin release
    • Ileum and colon release peptide YY, which binds to ECLs
  47. Adenamotous polyp formation association with what factor
    COX-2 overexpression
  48. Recurrence prevention of ulcers
    Antibiotics
  49. Hemachromatosis mechanism?
    • Chr 6.
    • HFE gene encodes a HLA-class I transporter that affects Fe absorption in the duodenum
  50. Crohn's disease affected with what transcription factor?
    NF-kB causes cytokine production
  51. Hox genes encode what factors? 
    Transcription regulators encoding morphogenesis.
  52. Abnormal midgut rotation around SMA?
    • 1. Intestinal obstruction
    • 2. Midgut volvulus (intestinal ischemia
  53. Bilous vomiting
    • 1. Duodenal atresia (ischemia)
    • 2. Intestinal obstruction distal to duodenum (ampulla of Vater)
  54. Function of MMC (migratory motor complexes)
    • Peristalsis waves from the stomach to the small intestine when food is not present. 
    • Sweeps undigested food and maintains low bacterial counts in the SI.
  55. Absence of MMC
    • Increased intestinal bacteria
    • Decreased gastric emptying
    • Slows duodenal motility
  56. ELEK test
    Identifies C.diptheria from other oropharynx flora
  57. CAMP test
    CAMP factor produced by S.agalactaie - used to distinguish between Group A and B strep
  58. Fats, proteins, and carbs together release what hormone
    GIP
  59. Treatment of nausea with anti-neoplastic agents?
    • 1. 5HT3 antagonists (Ondasteron)
    • 2. Cental dopamine antagonists (Metachlopromide)
  60. Acute hemorrhagic pancreatitis
    Necrosis and hemorrhage --> Septic shock
  61. Arepritant
    • NK-1 antagonist and block susbtance P
    • (NK receptors present in the brainstem and control the emetic reflex)
    • Treats nausea and vomiting with moderate anti-neoplastic agents
  62. MCAD deficiency
    • Accumulation of acylcarinitines in the urine
    • B-oxidation impairment - low ATP levels
    • Low ATP = deficiency of urea cycle
    • Urea cycle def = hyperammonia
    • Fasting hypoglycemia (low glucagon)
    • No ketone bodies
  63. CCK
    • Inhibits gastric acid secretion via somatostain
    • Inhibits gastric emptying
    • Contraction of gallbladder and relaxation of sphincter of Oddi
    • Digestion in the duodenum
    • Increases production of hepatic bile 

    n.b. CCK antagonist can also increase CCK levels
  64. Reyes syndrome pathophysiology
    • Encephalopathy and hepatic failure
    • Mitochondrial dysfunction: impairs B-oxidation and oxidative phosphorylation (glycolysis)
  65. Causes of jejunal and ileal obstruction
    • Ascaris infection
    • Hernias
    • Adhesions 
    • Tumors - intessuception
    • Midgut volvulus
  66. What strengthens gastric mucosal barrier?
    • Mucus (impedes H+ ion flow)
    • Gastrin (mucosal growth)
  67. Acini in sublingual glands
    Mucus
  68. Acini in the parotid gland
    Serous 
  69. Acini in the submucosal glands
    Serous + Mucus
  70. What stimulates gastric acid secretion
    • 1. Gastrin 
    • 2. Ach (vagal stimulation)
    • 3. Histamine
  71. What inhibits gastric acid secretion and stimulates pancreas to release HCO3?
    • Secretin
    • VIP
  72. Enzymes in hepatic injury caused by acetaminophen
    • Increased AST and ALT
    • Normal amylase (no pancreatitis)
    • Normal ALP (no injury to the bile ducts or biliary tree)
  73. Pressure on splenic a. affects what artery
    • Short gastric
    • (left gastroepiploic anastomoses with right gastroepiploic)
  74. How is NH3 excreted?
    • Mainly by conversion from NH3 to urea by the urea cycle in the liver
    • (Liver disease inhibits this causing encephalopathy)
    • Excreted as free acid (NH4+) by the kidney (minimally)
  75. H. pylori damaging gastric mucosa
    • Urease causes breakdown of urea into NH4+ increasing acidity, and feedback inhibition onto gastrin. 
    • Bacteria can survive acid environment of stomach
    • Damage to mucosa causes ulcer formation
  76. Sclerodactaly and esophageal dysmotility
    Increased fibrosis causes thickening of skin in esophagus, making it difficult to swallow, causes heartburn, absence of persistalsis and LES
  77. Obstructive jaundice due to gallstones
    • Increased conjugative bilirubin
    • Increased urine bilirubin (colour of urine darkens)
    • Decreased urobilinogen (therefore, clay coloured stools)
  78. Pigmented gallstones causes
    • Hemolytic anemias
    • Cirrhosis
    • Clonorchis sinesis (liver fluke)
  79. Multiple nests of benign, disorganized hepatic parenchyma containing biliary components 
    • Focal nodular hyperplasia 
    • (variant of HCC)
  80. GE junction seen above the esophageal hiatus of the diaphragm
    Sliding hiatal hernia
  81. Paraesophageal hiatal hernia
    • Part of gastric cardia slides up into the thorax, alongside the esophagus. 
    • GE junction is at the esophageal hiatus (not displaced)
  82. Treatment of traveller's diarrhea
    Fluoroquinolones (mostly for gram negatives)
  83. Duodenal atresia
    • Failure of recanalization of the embryonic duct = intestinal obstruction
    • Bilous vomiting after feeding
    • Two air-filled structures in the stomach
    • No distal air bowel gas
  84. Necrotizing enterocolitis
    • Occurs when oral foods are introduced in preemies mostly
    • Ischemic injury of the gut leading to septic shock
    • Affected mostly with giving formula rather than breastmilk - lack of maternal antibodies. 
    • Do pass meconium on 1st day
  85. Diarrhea that is treated with nutrient supplementation
    • Osmotic diarrhea 
    • (unabsorbed solutes draw water in)
  86. Treat of acute choecystitis with a codeine drug
    • Meperidine: M3 antagonist so it causes relaxation of the spincter 
    • (Morphine causes contraction of the sphincter, even though a good pain reliever)
  87. Cystic-fibrosis induced pancreatitis
    Reduced secretions causes thickened mucus plugs = accumulation of pancreatic enzymes
  88. Gastric heterotropia
    Can occur in the SI and produce enough acid to cause peptic ulcers and then bleeding
  89. Hepatic fibrosis without fat accumulation, and accumulation of small-chain dextrin like material in the hepatocytes.
    Cori's disease: debranching enzyme defect = incomplete glycogen degradation (a,1,6 glucosidic bonds cannot be broken)
  90. Why does RNA polymerase make many errors during replication?
    Doesn't have 3'-5' exonuclease activity
  91. Ulcerative colitis leads to colorectal cancer long-term. Features?
    • Arises from dysplastic flat lesions (no polyps)
    • Early p53 mutations and late APC gene mutations
    • Multifocal in nature
    • Histo: mucinous and/or signet ring morphology
  92. Interupting migration of neural crest cells damages what part of the GI tract first
    • Hirschrpung's dz: Rectum
    • Vagal stimulated: NC cells give rise to Meissner's (submucosal) and Auberbach plexi (myenteric)
    • NC cell migration moves caudally
  93. Pancreatic pseudocyst
    • Complication of pancreatitis
    • Fluid-filled with enzymes and inflammatory debris
    • Walls have granulation tissue and fibrosis, no epithelium
  94. Causes of esophagitis and findings
    • Candida
    • Herpes simplex - small vesicles with punched out lesions, eosinophilic intranuclear inclusions
    • CMV - linear ulceration, intranuclear and intracytoplasmic inclusion bodies
  95. Ulcerative colitis patient develops bloody diarrhea and abdominal distention. Dx?
    • Toxic megacolon - supportive treatment
    • (barium enema and colonscopy can cause perforation)
  96. Systemic mastocytosis
    Mast cell proliferation in multiple organs. Massive release of histamine - acts on parietal cells to stimulate gastric acid - inactivates pancreatic and intestinal enzymes - diarrhea, etc.
  97. Vibrio cholera
    • Toxin mediated watery diarrhea (increased cAMP)
    • Not invasive 
    • No blood or pus (leukocytes) on stool microscopy
  98. Lactase deficiency (biochemical process)?
    • Enzyme: B-galactosidase
    • Galactosyl-B-1,4glucose --> Galactose
  99. Opiod adverse effects in GI
    Contraction of smooth muscle cells of the sphicter of Oddi, increasing pressure in bile duct and gallbladder (biliary colic)
  100. Anal fissures
    • Located on posterior midline distal to the dentate line
    • Severe tearing pain when needed to pass stool
    • Due to low fibre diets and constipation
  101. Polyps progression to cancer process:
    • 1. APC gene mutation causes adenomatous polyps to form from normal colonic mucosa
    • 2. K-ras mutation = cell proliferation (size increase in polyps)
    • 3. p53 mutation - last step from adenoma to carcinoma
  102. Where are fats and fat-soluble vitamins digested and absorbed?
    Duodenum and jejunem
  103. Serum sickness
    • Type III H.S.
    • 5-10 days after drug given
    • Sx: arthralgias, utricaria, proteinuria, lymphadenopathy
  104. Crohn's disease molecular factors
    Increased TH1 helper cells = increases IFN-gamma, IL-2, and TNF causing intestinal injury.
  105. Elevated serum transaminases, neurological sx, no viral serologies, no use of alcohol or drugs.
    Dx?
    • Wilson's dz
    • Chr 13
    • AR
  106. Location of promoter regions?
    25-70 bp upstream from its associated gene
  107. Location of enhancers/repressors?
    Variable: upstream, downstream, or within the transcribed gene
  108. Shigella pathogenesis
    • Mucosal invasion by entering M cells via Peyer's patches
    • Escapes phagosome and enters epithelial cells to release shiga toxin
  109. Use of primaquine with chloroquine
    • Chloroquine has no effect against latent hepatic infections (P.vivax and P.ovale)
    • Primaquine used to treat these and prevent relapse
  110. Hydatid cysts
    • Cause: E.granulosus (tapeworm)
    • Aspiration of cyst leads to anaphylactic shock
  111. Moldy grains
    • Aflatoxin
    • Gene mutation in p53
    • Prone to HCC
  112. Villous adenoma
    • Mucoid, secretory diarrhea
    • Mass found in sigmoid colon (obstruction)
    • Lower intestinal bleeding
    • Progresses to adenocarcinoma
  113. H.pylori and duodenal ulcers
    • Antral gastritis: decreased # of somatostatin-antral producing cells
    • High gastrin causes high acidity 
  114. H.pylori and gastric ulcers
    • Dont need an increase level of acid
    • Normal acid levels are sufficient as in the stomach
    • Destruction of mucosal barrier due to bacteria
  115. Secretion of gastrin
    Secretion of HCl and IF
    • G cells of the gastric antrum
    • Fundus
  116. What happens with vagotomy?
    • Receptive relaxation is inhibited (cannot relax when food enters the stomach from the esophagus)
    • Peristalsis can still occur
  117. Cholera toxin mechanism
    Activates AC increasing cAMP in the intestinal crypt cells activating Cl- secretory channels
  118. Micelles solubilize what?
    Fat soluble vitamins

    • n.b. Bile acids have a co-dependent Na+ transport in ileum
    • Glycerol is a water soluble molecule of lipid digestion and doesnt need micelles
  119. Secretion from exocrine pancreas (enzymes)
    • Major anion is HCO3 in pancreatic secretions (higher than plasma)
    • Cl- is lower than plasma
    • Stimulated by presence of fatty acids in the duodenum

    • Secretin stimulates pancreatic HCO3 secretions
    • CCK stimulates pancreatic enzyme secretions
  120. Oral glucose better than IV glucose
    Releases GIP which causes release of insulin from endocrine pancreas
  121. Features of saliva
    • Hypotonic
    • High HCO3- relative to plasma
    • Presence of a-amylase and lingual lipase
    • No proteases
  122. Contamination from poultry foods causing watery diarrhea
    • Campylobacter (take couple of days to develop)
    • Salmonella non-typhi
    • S.aureus (immediate, within hours)
  123. Where are Kaposi's sarcoma nodules found?
    All over the body, including skin and GI tract mucosa
  124. Spontaneous bacterial peritonitis
    • Seen in 10% of patients who have cirrhosis with ascites
    • Ascites: culture medium for bacteria that invade the bowel wall or spread to serosa
    • E.coli
  125. Entire eroded gastric mucosa with erythematous, cobble-stone appearance. Stomach is small and shrunken.
    Signet cell adenocarcinoma
  126. 11-month old with no stool on diaper and distended abdomen

    At birth, no stool on diaper and distended abdomen
    Intussusception

    Hirshprung's disease
  127. Gastric defenses against peptic ulcer disease
    • HCO3 secretion into the mucus
    • Rapid gastric epithelial regeneration
    • Epithelial cell mucus secretion
    • Increased mucosal blood flow

    n.b delayed gastric emptying promotes ulcers by keeping acid in there
  128. Which bug causes diarrhea in young children that can be replaced with adequate fluids?
    Rotavirus
  129. Complications of diverticulosis
    Diverticulitis producing an abscess, peritonitis or both. 
  130. Cancers of the GI tract associated with AIDS and non-AIDS.
    • B cell neoplasms:
    • a) Kaposi's sarcoma
    • b) non-Hodgkin's lymphoma
    • c) anorectal SCC

    Non-AIDS: MALT lymphomas with sprue, H.pylori infection

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