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UWorld Journal > GI > Flashcards

GI Flashcards

1
Q

how does galactokinase deficiency causes cataracts

A

buildup of galactose–> converted to galactitol, an osmostic agent that causes cataracts

may present as failure to track objects or to develop a social smile

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2
Q

MHC Class _____ requires acidification of lysosomes to be expressed and bound to foreign antigen

A

II

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3
Q

what can be used to differentiate between pancreatic vs. mucosal causes of malabsorption

A

D-xylose absorption

monosaccharides don’t need pancreatic and brush border amylases to be absorbed- they can be absorbed directly

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4
Q

what enzyme is used to convert trypsinogen to trypsin

A

enteropeptidase—>

deficiency leads to protein and fat malabsorption–> diarrhea, failure to thrive, and edema (from hypoproteinemia)

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5
Q

side effect of fibrates

A

cholesterol stones

fibrates inhibit cholesterol 7alpha-hydroxylase which help synthesize bile acids. with less bile acids,–> decreased cholesterol solubility in bile

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6
Q

periodic acid-Schiff (PAS) stain identifies ______

A

glycogen

help with diagnosing glycogen storage diseases

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7
Q

clinical manifestation of riboflavin (vitamin B2) deficiency

A

angular stomatitis, cheilitis (inflammation of the lips), glossitis, seborrheic dermatitis, eye changes, and anemia

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8
Q

role of riboflavin (vitamin B2)- containing coenzymes

A

make up part of the electron transport chain

precursor of the coenzymes FMN and FAD

FAD=component of succinate dehydrogenase (complex II)

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9
Q

mechanism of action for ribavirin

A

interfere with the duplication of viral genetic material

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10
Q

iron is absorbed in

A

duodenum

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11
Q

folate is absorbed in

A

small bowel

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12
Q

vitamin B12 is absorbed in

A

terminal ileum along with bile salts, requires intrinsic factor

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13
Q

what is the surgical landmark used for appendectomy

A

teniae coli— 3 bands that travel on the outside of the entire colon before converging at the root of the veriform appendix

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14
Q

to encircle the supper stomach, the gastric band must pass through the ____________

A

less omentum

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15
Q

what is Crigler-Najjar syndrome

A

autosomal recessive
impaired bilirubin metabolism caused by a genetic lack of the UGT enzyme needed to catalyze bile glucuronidation–> hyperbilirubinemia in infants–> kernicerus (bilirubin in brain) and death

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16
Q

increased activity of ____________ cells play a role in Crohn’s disease

A

TH-1 helper

increase production IL-2, interferon-gamma, and TNF–> cause more intestinal injury

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17
Q

result of alpha-1 antitrypsin deficiency

A

panacinar emphysema and liver disease (cirrhosis and hepatocellular carcinoma)

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18
Q

Budd-Chiari syndrome-what is it

A

obstruction of venous outflow from the liver

present with acute or subacute liver failure or asymptomatic

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19
Q

how would someone with chronic mesenteric ischemia present?

A

postprandial epigastric pain and associated food aversion/weight loss in the settling of generalized atherosclerosis (eg, coronary and carotid artery disease)

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20
Q

biopsy of which part of the GI tract will be most helpful to diagnose Celiac disease

A

duodenal

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21
Q

what is protective for women against hemochromatosis?

A

physiologic iron loss through menstruation and pregnancy

hemochromatosis– gradual buildup of iron–> skin pigmentation, hepatomegaly, impaired glucose homeostasis, cardiac dysfunction, atypical arthritis, hypogonadism

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22
Q

right-sided colon cancers vs. left-sided colon cancers

A

right: grow as exophytic masses and present with occult bleeding and symptom of iron deficiency anemia
left: infiltrate intestinal wall and encircle lumen–> constipation and symptoms of intestinal obstruction

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23
Q

the walls of pancreatic pseudocyst is made u p of:

A

granulation tissue and fibrosis, not epithelium

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24
Q

what is needed to activate hepatitis D virus

A

it needs to be coated by external coat hepatitis B surface antigen of HBV to penetrate the hepatocyte

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25
Q

3 main causes of HIV-associated esophagitis

A

Candida (patches of adherent, grey/white pseudomembranes)

Cytomegalovirus (large, shallow linear ulcerations) (enlarged cells with intranuclear inclusions)

herpes simplex virus (small vesicles “punched-out” ulcers)

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26
Q

what is Kehr sign

A

shoulder pain in the C3-C5 region (phrenic nerve) represents referred pain due to peritoneal irritation

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27
Q

define ectompy

A

identifies microscopically and functionally normal cells/tissues found in an abnormal location due to embryonic maldevelopment

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28
Q

increased pressure in what vessel would lead to gastric varices only in the fundus

A

splenic vein– blood clot here will increase pressure in the short gastric veins and cause gastric varices

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29
Q

base excision repair steps

A

glycosylase (cleaves altered base)–> endonuclease (cleaves 5’ end)–> lyase (cleaves 3’ sugar-phosphate)–> DNA polymerase (fills single nucleotide gap)–> ligase (seals nick)

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30
Q

what lab findings would be most indicative of poor prognosis for alcoholic cirrhosis?

A

serum albumin levels (low) and prothrombin time (high)

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31
Q

process of forming Zenker diverticulum

A

abnormal spasm or diminished relaxation of the cricopharyngeal muscles during swallowing (cricopharyngeal motor dysfunction)–> early oropharyngeal dysphagia–> herniation of the pharyngeal mucosa through the zone of muscle weakness (false diverticulum) in the posterior hypopharynx (Killian triangle)

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32
Q

hyperammonemia- how does this disrupt excitatory neurotransmission

A

astrocytes use ammonia to convert glutamate to glutamine–> glutamine released and taken up by neurons and converted back to glutamate

excess ammonia–> too much glutamine and astrocyte can’t release glutamine so decrease conversion to glutamate

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33
Q

why would liver cirrhosis lead to gynecomastia?

A

impaired estrogen metabolism by liver–> gynecomastia, testicular atrophy, decreased body hair, spider aniomata (usually seen in pregnancy)

34
Q

calculate bioavailbility

A

area under oral curve divided by area under IV curve

35
Q

drug used to teat arsenic poisoning (found in insecticides)

A

dimercaprol= chelating agent

36
Q

major immune mechanism against Giardia

A

CD4+ T helper cells and secretory IgA production (prevent giardia from adhering to the intestinal brush border and causing damage in the duodenum and jejunum)

37
Q

strictures and fistulas (complications of Crohn’s disease) are caused by

A

transmural inflammation–> edema and fibrosis

38
Q

vessels in the portal triad

A

hepatic artery, hepatic portal vein, common bile duct

all run through hepatoduodenal ligament

39
Q

clinical features of vitamin A deficiency

how can people become vitamin A deficient

A

night blindness, severe eye dryness and corneal ulceration, hyperkeratosis (thickened, dry skin), growth retardation

due to malabsorption related to biliary obstruction, exocrine pancreatic insufficiency, or small-bowel resection

40
Q

what is Sudan III stain used for

A

test stool for fat to screen for malabsorptive disorders

41
Q

parietal cells secrete

A

gastric acid (HCl) and intrinsic factor

located in gastric glands of the fundus and body of the stomach

42
Q

where do you find Helicobacter pylori that cause duodenal ulcers

A

greatest concentration in the prepyloric area of the gastric antrum

43
Q

first symptom reported for primary biliary cirrhosis

A

severe pruritus (especially at night)

most common in middle-aged women

autoimmune destruction of the intrahepatic bile ducts and cholestasis (eleated alkaline phosphatase)

44
Q

porcelain gallbladder is associated with increased risk of

A

gallbladder adenocarcinoma

-porcelain= calcified gallbladder

45
Q

Crohn disease is associated with mutations in

A

NOD2 (encodes intracellular microbial receptor)–> decreased activity of the NF-kB protein (proinflammatory transcription factor) with reduced cytokin production

46
Q

histamine induces ______ secretion

A

gastric acid

lead to gastric ulceration

47
Q

mutation associated with Lynch synrome

A

defective DNA mismatch repair–> mutation in MSH2 and MLH1

-hereditary nonpolyposis colon cancer, endometrial cancer, ovarian cancer

auto dominant

48
Q

inherited defects involving what pathway resul in disseminated mycobacterial disease in infancy or early childhood

A

interferon-gamma signaling pathway

49
Q

define Curling ulcers

A

ulcers arising in proximal duodenum in association with severe trauma/burns

50
Q

define Cushing ulcers

A

ulcers arising in the esophagus, stomach, or duodenum in patients with intracranial injury

-consequence of direct vagus nerve stimulation caused by elevated intracranial pressure–> acetylcholine release and hypersecretion of gastric acid

51
Q

mechanism of action of Fidaxomicin

A

macrocyclic antibiotic that inhibits the sigma subunit of RNA polymerase–> protein synthesis impairment and cell death (bacteriocidal against recurrent C. difficile)

52
Q

compare sporadic colorectal carcinomas with colitis-associated carcinomsa

A

colitis-associated: arise from non-polypoid dysplastic lesion, multifocal in nature, develop early p53 mutations and late APC gene mutations, higher histological grade

sporadic: arise from polypoid lesions

53
Q

direct inguinal hernias are covered by _______ fascia, while indirect inguinal hernias are covered by _________ fascial layer (s)

A

external spermatic fascia; all 3 spermatic fascial layers

54
Q

pathophysiology of indirect inguinal, direct inguinal and femoral hernias

A

indirect: patent processus vaginalis (see with male infants)
direct: weak transversalis fascia (see with older men)
femoral: weak proximal femoral canal (see with women)

55
Q

how can opioid analgesics increase pressure int he common bile duct and the gallbladder?

A

cause contraction of smooth muscle in the sphincter of Oddi

56
Q

crohn disease is associated with _______ stones

A

oxalate kidney stones due to impaired bile acid absorption in the terminal ileum–> fat malabsorption that bind to calcium and result in free oxalate

57
Q

watershed areas of the colon

A

splenic flexure and rectosigmoid junction

58
Q

what is superior mesenteric artery syndrome

A

compression of the transverse (third) portion of the duodenum between the SMA and the aorta–> intermittent intestinal obstruction symptoms

associated with diminished mesenteric fat like low body weight/malnutrition

59
Q

Dubin-Johnson syndrome

A

benign autosomal recessive disorder characterized by defective hepatic excretion of bilirubin glucuronides due to mutation in the canalicular membrane transport protein

liver appears black b/c impaired excretion of epinephrine metabolites that accumulate in lysosomes

60
Q

which hepatitis is associated with significant elevations in aspartate aminotransferase and alanine aminotransferse, often >10 times the upper limit of normal

A

acute HBV

61
Q

necrotizing enterocolitis-what is it?

A

bacterial invasion and ischemic necrosis of bowel wall

associated with prematurity and initiation of enteral feeding

x-ray shows pneumatosis (air in bowel wall)

62
Q

what is cirrhosis characterized by

A

diffuse hepatic fibrosis with replacement of the normal lobular architecture by fibrous-lined parenchymal nodules

63
Q

histology of acute hepatitis A infection

A

“spotty necrosis” with ballooning degeneration (hepatocyte swilling with wispy/clear cytoplasm), Councilman bodies (eosinophilic apoptotic hepatocytes), and mononuclear cell infiltrates

64
Q

series of gene mutations called adenoma to carcinoma sequence

A

1) APC mutation–> normal mucosa to small adenomatous polyp (adenoma)
2) KRAS mutation–> increase is size of adenoma
3) TP53 mutation=-> transform adenoma into carcinoma

65
Q

why can villous adenomas cause secretory diarrhea?

A

can secrete large quantities of watery mucus–> secretory diarrhea, hypovolemia, and electrolyte abonormalities

66
Q

nonsurgical treatment for cholesterol gallstones

A

hydrophilic bile acids

–> reduce cholesterol secretion and increases biliary bile acid concentration–> promotes gallstone dissolution

67
Q

main mechanism of excess copper removal

A

hepatic excretion into bile

68
Q

mechanism of action for Statins

A

inhibit HMG CoA reductase–> decreases hepatic cholesterol synthesis–> upregulate LDL receptors–> decrease LDL cholesterol

69
Q

what drugs are the most effective for motion sickness prevention

A

antimuscarinic agents and antihistamines with antimuscarinic action

70
Q

weird thing about how gastric G cells reaction to secretin in Zollinger-Ellison syndrome

A

ZES- when you administer secretin, this increases gastrin levels

normal- secretion would inhibit release of gastrin form normal gastric G cells

71
Q

anal fissures occur at the __________

A

posterior midline distal to the dentate line–> due to decreased blood flow in this area

72
Q

where is majority of the plasma LDL cleared

A

in the liver– have lots of LDL receptors

73
Q

elevated pressure in ______ in liver cirrhosis

A

portal system

74
Q

characteristics of primary biliary cirrhosis/cholangitis

A

autoimmune liver disease with destruction of intrahepatic, interlobular bile ducts by granulomatous inflammation

-pruritus and fatigue in middle-aged women

–>cholestasis (jaundice, pale stool, dark urine) and hypercholesterolemia

75
Q

cephalic and gastric phases _______ gastric acid secretion, while intestinal influences tend to _____ gastric acid secretion

A

stimulate; reduce

76
Q

conditions that cause GI irritation–> increased mucosal _______ release and activation of _________ on vagal and spinal afferent nerves

A

serotonin; 5-Ht3 receptors

–> relay their impulses to the medullary vomiting center

77
Q

Mallory-Weiss syndrome- tears occur secondar to

A

rapid increase in intraabdominal and intraluminal gastric pressure (retching and vomiting)

half of patients have hiatal hernias

78
Q

what do you see in esophageal manometry in achalasia

A

decreased amplitude of peristalsis in the mid esophagus with increased tone and incomplete relaxation at the lower esophageal sphincter

79
Q

what laboratory measurements can you use to differentiate between alcohol-related acute pancreatitis and pancreatitis due to other causes

A

macrocytosis (mean corpuscular volume >100 fL) related to poor nutrition like folate deficiency, liver disease, and/or direct toxicity of alcohol on the marrow

80
Q

how to determine whether an elevated alkaline phosphatase is of hepatic or bony origin since it is produced by both bone and liver

A

gamma-glutamyl transpeptidase

-enzyme in hepatocyes and biliary epithelia so if elevated then know that the alkaline phosphatase came from the liver

81
Q

vomiting is a reflex regulated by which 5 receptors

A

M1 muscarinic, D2 dopaminergic, H1 histaminic, 5-HT3 serotonergic, and neurokinin 1 (NK1) receptors

5-HT3 and NK1 receptor antagonists are particularly useful for chemotherapy-induced vomiting

UWorld Journal (18 decks)

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