GI Flashcards
how does galactokinase deficiency causes cataracts
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
MHC Class _____ requires acidification of lysosomes to be expressed and bound to foreign antigen
II
what can be used to differentiate between pancreatic vs. mucosal causes of malabsorption
D-xylose absorption
monosaccharides don’t need pancreatic and brush border amylases to be absorbed- they can be absorbed directly
what enzyme is used to convert trypsinogen to trypsin
enteropeptidase—>
deficiency leads to protein and fat malabsorption–> diarrhea, failure to thrive, and edema (from hypoproteinemia)
side effect of fibrates
cholesterol stones
fibrates inhibit cholesterol 7alpha-hydroxylase which help synthesize bile acids. with less bile acids,–> decreased cholesterol solubility in bile
periodic acid-Schiff (PAS) stain identifies ______
glycogen
help with diagnosing glycogen storage diseases
clinical manifestation of riboflavin (vitamin B2) deficiency
angular stomatitis, cheilitis (inflammation of the lips), glossitis, seborrheic dermatitis, eye changes, and anemia
role of riboflavin (vitamin B2)- containing coenzymes
make up part of the electron transport chain
precursor of the coenzymes FMN and FAD
FAD=component of succinate dehydrogenase (complex II)
mechanism of action for ribavirin
interfere with the duplication of viral genetic material
iron is absorbed in
duodenum
folate is absorbed in
small bowel
vitamin B12 is absorbed in
terminal ileum along with bile salts, requires intrinsic factor
what is the surgical landmark used for appendectomy
teniae coli— 3 bands that travel on the outside of the entire colon before converging at the root of the veriform appendix
to encircle the supper stomach, the gastric band must pass through the ____________
less omentum
what is Crigler-Najjar syndrome
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
increased activity of ____________ cells play a role in Crohn’s disease
TH-1 helper
increase production IL-2, interferon-gamma, and TNF–> cause more intestinal injury
result of alpha-1 antitrypsin deficiency
panacinar emphysema and liver disease (cirrhosis and hepatocellular carcinoma)
Budd-Chiari syndrome-what is it
obstruction of venous outflow from the liver
present with acute or subacute liver failure or asymptomatic
how would someone with chronic mesenteric ischemia present?
postprandial epigastric pain and associated food aversion/weight loss in the settling of generalized atherosclerosis (eg, coronary and carotid artery disease)
biopsy of which part of the GI tract will be most helpful to diagnose Celiac disease
duodenal
what is protective for women against hemochromatosis?
physiologic iron loss through menstruation and pregnancy
hemochromatosis– gradual buildup of iron–> skin pigmentation, hepatomegaly, impaired glucose homeostasis, cardiac dysfunction, atypical arthritis, hypogonadism
right-sided colon cancers vs. left-sided colon cancers
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
the walls of pancreatic pseudocyst is made u p of:
granulation tissue and fibrosis, not epithelium
what is needed to activate hepatitis D virus
it needs to be coated by external coat hepatitis B surface antigen of HBV to penetrate the hepatocyte
3 main causes of HIV-associated esophagitis
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)
what is Kehr sign
shoulder pain in the C3-C5 region (phrenic nerve) represents referred pain due to peritoneal irritation
define ectompy
identifies microscopically and functionally normal cells/tissues found in an abnormal location due to embryonic maldevelopment
increased pressure in what vessel would lead to gastric varices only in the fundus
splenic vein– blood clot here will increase pressure in the short gastric veins and cause gastric varices
base excision repair steps
glycosylase (cleaves altered base)–> endonuclease (cleaves 5’ end)–> lyase (cleaves 3’ sugar-phosphate)–> DNA polymerase (fills single nucleotide gap)–> ligase (seals nick)
what lab findings would be most indicative of poor prognosis for alcoholic cirrhosis?
serum albumin levels (low) and prothrombin time (high)
process of forming Zenker diverticulum
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)
hyperammonemia- how does this disrupt excitatory neurotransmission
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
why would liver cirrhosis lead to gynecomastia?
impaired estrogen metabolism by liver–> gynecomastia, testicular atrophy, decreased body hair, spider aniomata (usually seen in pregnancy)
calculate bioavailbility
area under oral curve divided by area under IV curve
drug used to teat arsenic poisoning (found in insecticides)
dimercaprol= chelating agent
major immune mechanism against Giardia
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)
strictures and fistulas (complications of Crohn’s disease) are caused by
transmural inflammation–> edema and fibrosis
vessels in the portal triad
hepatic artery, hepatic portal vein, common bile duct
all run through hepatoduodenal ligament
clinical features of vitamin A deficiency
how can people become vitamin A deficient
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
what is Sudan III stain used for
test stool for fat to screen for malabsorptive disorders
parietal cells secrete
gastric acid (HCl) and intrinsic factor
located in gastric glands of the fundus and body of the stomach
where do you find Helicobacter pylori that cause duodenal ulcers
greatest concentration in the prepyloric area of the gastric antrum
first symptom reported for primary biliary cirrhosis
severe pruritus (especially at night)
most common in middle-aged women
autoimmune destruction of the intrahepatic bile ducts and cholestasis (eleated alkaline phosphatase)
porcelain gallbladder is associated with increased risk of
gallbladder adenocarcinoma
-porcelain= calcified gallbladder
Crohn disease is associated with mutations in
NOD2 (encodes intracellular microbial receptor)–> decreased activity of the NF-kB protein (proinflammatory transcription factor) with reduced cytokin production
histamine induces ______ secretion
gastric acid
lead to gastric ulceration
mutation associated with Lynch synrome
defective DNA mismatch repair–> mutation in MSH2 and MLH1
-hereditary nonpolyposis colon cancer, endometrial cancer, ovarian cancer
auto dominant
inherited defects involving what pathway resul in disseminated mycobacterial disease in infancy or early childhood
interferon-gamma signaling pathway
define Curling ulcers
ulcers arising in proximal duodenum in association with severe trauma/burns
define Cushing ulcers
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
mechanism of action of Fidaxomicin
macrocyclic antibiotic that inhibits the sigma subunit of RNA polymerase–> protein synthesis impairment and cell death (bacteriocidal against recurrent C. difficile)
compare sporadic colorectal carcinomas with colitis-associated carcinomsa
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
direct inguinal hernias are covered by _______ fascia, while indirect inguinal hernias are covered by _________ fascial layer (s)
external spermatic fascia; all 3 spermatic fascial layers
pathophysiology of indirect inguinal, direct inguinal and femoral hernias
indirect: patent processus vaginalis (see with male infants)
direct: weak transversalis fascia (see with older men)
femoral: weak proximal femoral canal (see with women)
how can opioid analgesics increase pressure int he common bile duct and the gallbladder?
cause contraction of smooth muscle in the sphincter of Oddi
crohn disease is associated with _______ stones
oxalate kidney stones due to impaired bile acid absorption in the terminal ileum–> fat malabsorption that bind to calcium and result in free oxalate
watershed areas of the colon
splenic flexure and rectosigmoid junction
what is superior mesenteric artery syndrome
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
Dubin-Johnson syndrome
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
which hepatitis is associated with significant elevations in aspartate aminotransferase and alanine aminotransferse, often >10 times the upper limit of normal
acute HBV
necrotizing enterocolitis-what is it?
bacterial invasion and ischemic necrosis of bowel wall
associated with prematurity and initiation of enteral feeding
x-ray shows pneumatosis (air in bowel wall)
what is cirrhosis characterized by
diffuse hepatic fibrosis with replacement of the normal lobular architecture by fibrous-lined parenchymal nodules
histology of acute hepatitis A infection
“spotty necrosis” with ballooning degeneration (hepatocyte swilling with wispy/clear cytoplasm), Councilman bodies (eosinophilic apoptotic hepatocytes), and mononuclear cell infiltrates
series of gene mutations called adenoma to carcinoma sequence
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
why can villous adenomas cause secretory diarrhea?
can secrete large quantities of watery mucus–> secretory diarrhea, hypovolemia, and electrolyte abonormalities
nonsurgical treatment for cholesterol gallstones
hydrophilic bile acids
–> reduce cholesterol secretion and increases biliary bile acid concentration–> promotes gallstone dissolution
main mechanism of excess copper removal
hepatic excretion into bile
mechanism of action for Statins
inhibit HMG CoA reductase–> decreases hepatic cholesterol synthesis–> upregulate LDL receptors–> decrease LDL cholesterol
what drugs are the most effective for motion sickness prevention
antimuscarinic agents and antihistamines with antimuscarinic action
weird thing about how gastric G cells reaction to secretin in Zollinger-Ellison syndrome
ZES- when you administer secretin, this increases gastrin levels
normal- secretion would inhibit release of gastrin form normal gastric G cells
anal fissures occur at the __________
posterior midline distal to the dentate line–> due to decreased blood flow in this area
where is majority of the plasma LDL cleared
in the liver– have lots of LDL receptors
elevated pressure in ______ in liver cirrhosis
portal system
characteristics of primary biliary cirrhosis/cholangitis
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
cephalic and gastric phases _______ gastric acid secretion, while intestinal influences tend to _____ gastric acid secretion
stimulate; reduce
conditions that cause GI irritation–> increased mucosal _______ release and activation of _________ on vagal and spinal afferent nerves
serotonin; 5-Ht3 receptors
–> relay their impulses to the medullary vomiting center
Mallory-Weiss syndrome- tears occur secondar to
rapid increase in intraabdominal and intraluminal gastric pressure (retching and vomiting)
half of patients have hiatal hernias
what do you see in esophageal manometry in achalasia
decreased amplitude of peristalsis in the mid esophagus with increased tone and incomplete relaxation at the lower esophageal sphincter
what laboratory measurements can you use to differentiate between alcohol-related acute pancreatitis and pancreatitis due to other causes
macrocytosis (mean corpuscular volume >100 fL) related to poor nutrition like folate deficiency, liver disease, and/or direct toxicity of alcohol on the marrow
how to determine whether an elevated alkaline phosphatase is of hepatic or bony origin since it is produced by both bone and liver
gamma-glutamyl transpeptidase
-enzyme in hepatocyes and biliary epithelia so if elevated then know that the alkaline phosphatase came from the liver
vomiting is a reflex regulated by which 5 receptors
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
