U-World-Gastrointestinal Flashcards
list the four major types of non-neoplastic colonic polyps
four types of polyps= hyperplastic (well-differentiated mucosa with glands and crypts), hammartomatous (musoca, smooth muscle and connective tissue seen together), inflammatory (seen in IBD), lymphoid (often seen in children)
what kind of adenomatous polyp is carries higher risk of malignancy
villous adenoma
tubular adenoma has a lower associated risk
Meckel diverticulum is a remnant of what embryologic structure?
is it a true or false diverticulum?
Meckel diverticulum= remnant of omphalomesenteric (vitelline) duct
it is a true diverticulum (contains all four layers of gut wall)
how might Meckel diverticulum cause melena/hematochezia?
Meckel diverticula often contain ectopic gastric or pancreatic tissue
==> acid secretion ==> ulceration and GI bleeding
what characteristic abnormal cell type might you see in a Kaposi’s sarcoma lesion
spindle cells (elongated, stretched cells)
name the five major picornaviruses
which is acid-labile?
poliovirus, echovirus, rhinovirus, coxsackie A virus, hepatitis A virus
rhinovirus is acid-labile; therefore it cannot colonize the gut, just the respiratory tract
what are three common risk factors for gallbladder disease
“forty, fat and female”
epigastric pain following fatty meals is likely indirectly due to secretion of which hormone
CCK
in patients with biliary colic, the gallbladder is inflamed and when CCK is secreted it causes contraction of the inflamed gallbladder leading to pain
name three reducing sugars
fructose, glucose and galactose
manometric studies showing periodic non-peristaltic contractions of esophagus that are long in amplitude and duration and barium study showing “corckscrew esophagus” suggest what condition
diffuse esophageal spasm (DES)
what two main symptoms does diffuse esophageal spam cause
dysphagia and chest pain (not associated with exertion)
what immune mediator is most important in defense against Giardia lamblia
secretory IgA
patients with what genetic disorders are at especially increased risk of chronic Giardiasis
patients with X-linked agammaglobulinemia and common variable immune deficiency
(due to deficient IgA)
what disease can inhibited inactivation of trypsin cause
pancreatitis;
trypsin acts to inactivate itself (in addition to activating itself) and when it can’t do this accumulated trypsin in the pancreas leads to pancreatitis
what GI condition is diphenoxylate mainly used for and why
diphenoxylate is used to treat diarrhea;
it is an opioid and causes decreased GI motlity
in what particular location does MHC Class I bind its antigen vs. where MHC Class II binds its antigen
MHC Class I binds its antigen on the cell membrane vs.
MHC Class II which binds its antigen in the endosome
what are the two major causes of acute pancreatitis vs. less common causes
major causes: alcoholism, gallstones
less common: hypertriglyceridemia (causes cell toxicity), ERCP procedure, infection (Coxsackie, mycoplasma pneumoniae) drugs (sulfalazine, azathioprine, valproate, furosemide), structural abnormalities of the duct or ampulla, surgery, hypercalcemia
a patient from Peru with dysphagia and difficulty belching is shown to have a dilated esophagus with an area of absent peristalsis
what’s the likely microbe?
Trypanosoma cruzi
Chagas disease is associated with achalasia
what two ligaments make up the lesser omentum
hepatoduodenal ligament and hepatogastric ligament
what kind of ulcer is associated with H. pylori infection and decreased amount of somatostatin release
duodenal
note: gastric ulcer does not require increased HCl production
how do you differentiate between campylobacter jejuni, vibrio cholera and H. pylori (since all of them are gram negative, oxidase positive, comma-shaped rods)
campylobacter grows in 42 degrees Celcius
vibrio cholera grows in alkaline media
H. pylori produces urease
what would you see vs. not see in stool microscopy for a patient with cholera
mucus and some epithelial cells, but no leukocytes or lymphocytes because cholera doesn’t invade the mucosa
what do toxin A and toxin B of C. diff do
toxin A (enterotoxin) is a chemoattractant for neutrophils toxin B (cytotoxin) depolymerizes actin => loss of integrity of cytoskeleton
what vitamin must you supplement in patients who have had total gastrectomy
vitamin B12 (since the patient no longer has parietal cells to secrete intrinsic factor)
toxin from enterohemorrhagic E. coli is called what and acts via what mechanism?
what other toxin from what microbe acts via this same mechanism?
EHEC produces shiga-like toxin, aka verotoxin;
it degrades 28S rRNA by removing adenine and thereby inactivates the 60S ribosome
shiga-toxin from shigella has the same mechanism of action
what does 99mmTc-pertechnetate detect
99mmTc-pertechnetate detects gastric mucosa and can be used to detect ectopic gastric mucosa such as in Meckel diverticulum
what is the most common location for Crohn’s disease to manifest
terminal ileum
NK cells generally defend against what kinds of cells/pathology
NK cells defend against tumor cells or virus-infected cells
increased activity of what enzyme has been linked to recurrent adenomas of the colon
COX-2
what is the most important risk factor for developing esophageal adenocarcinoma
Barrett’s esophagus
what happens to the tissue of the esophagus in CREST syndrome
esophageal dysmotility is caused by atrophy and fibrous replacement of the esophageal muscles
a large cauliflower like mass in the colon is likely what kind of tumor
villous adenoma
what is the characteristic histological pattern of Celiac sprue
flattening of mucosa, atrophy of villi and inflammation of the lamina propria;
usually seen in duodenum and proximal jejunum
after a bout of viral gastroenteritis a young boy experiences abdominal distension and diarrhea that resolves upon restriction of dairy products; what is the enzyme deficiency involved and its associated reaction
lactase deficiency, secondary to gastroenteritis;
lactase is a beta-galactosidase that converts lactose to glucose and galactose
what happens to lipids in the duodenum vs. jejunum
lipids are digested in the duodenum and absorbed in the jejunum along with fat soluble vitamines (A,D, E, K)
in an infant with constipation and abdominal distension you see narrowing of the rectum and recto-sigmoid area on barium test; what part of the colon would you biopsy and what layer of the colon wall
you’d suspect Hirschsprung’s in a child this young with colonic narrowing
biopsy the submucosa of the narrow part of the colon to check for absence of ganglion cells of Meissner’s or Auerbach’s plexus
which part of the intestines is always involved in Hirschsprung’s disease
the rectum
list the 5 enzymatic steps of base excision repair
- glycosylase cleave out the base leaving an AP site
- endonuclease cleaves the 5’ end of the backbone
- lyase cleaves the 3’ end of the backbone
- DNA polymerase adds in the correct nucleotide
- ligase joins the ends of the nucleotide to the rest of the DNA strand
what are the two most common causes of acute pancreatitis
alcohol abuse and gallstones
what three structures does the ventral pancreatic bud become
uncinate process, inferior portion of the head of the pancreas, major pancreatic duct (of Wirsung)
via what mechanism does IgA protease work
IgA protease cleaves the IgA molecule at the hinge region allowing for organisms that secrete it (e.g. S. pneumo, Neisseria) to invade mucosal surfaces
what are the two forms of IgA and when is each form seen
IgA is a monomer in the bloodstream secretory IgA (found in mucosal surfaces) is a dimer with J chain and secretory component
what is the duodenal bulb
the segment of the duodenum beginning after the antrum of the stomach and ending at the neck of the gallbladder
when a duodenal ulcer penetrates into a blood vessel, which artery is likely involved
gastroduodenal artery (posterior wall ulcers are more prone to hemorrhage while anterior wall ulcers are more prone to perforation)
list 3 actions of VIP and name the syndrome caused by VIPoma
VIP decreases HCl production, relaxes GI smooth muscle and increases pancreatic bicarb and chloride secretion
VIPoma causes WDHA syndrome (watery diarrhea, hypokalemia and achlohydria)
pseudocysts, which can form after acute pancreatitis, tend to occur where?
what are their walls lined with?
pseudocysts tend to occur in the lesser peritoneal sac, just posterior to the stomach and duodenum
is a Cushing ulcer considered acute gastritis or peptic ulcer disease
acute gastritis
nyctalopia and dry skin suggest which vitamin deficiency
nyctalopia (night blindness) and dry skin suggest vitamin A deficiency
a patient born with imperforate anus will most likely have defects of what other body system
urogenital tract
what is the treatment for Giardia
metronidazole
is an ulcer of the distal duodenum more suggestive of a neoplastic condition or infectious condition
distal duodenal ulcers suggest Zollinger-Ellison (gastrinoma)
what is gallstone ileus and what are the x-ray findings
a gallstone passes from the gallbladder into the small intestines through a fistula formed by pressure of the tissues against each other;
the stone passes into the ileum, but gets stuck at the ileocecal valve;
on x-ray air can be seen in the gall bladder and biliary tree
what are the two main metabolites that get depleted in the brain during ammonia toxicity
glutamate and alpha-ketoglutarate are depleted:
excess ammonia leads to conversion of glutamate to glutamine and conversion of NH4+ to glutamate using alpha-ketoglutarate
how does ribavirin work and what GI disease is it used to treat
ribavirin treats HCV;
ribavirin is a nucleoside antimetabolite that interferes with viral replication by incorporating itself into viral RNA and causing hypermutation, among other things
constipation, abdominal colic and headaches suggest poisoning with iron or lead?
lead;
iron poisoning causes diarrhea and sometimes hemorrhage
which immune cells prevent superficial Candida infection?
which immune cells prevent disseminated (hematogenous spread) Candida infection?
Th cells prevent superficial infection
neutrophils prevent hematogenous spread of Candida
what would you find in the gallbladder of a patient with a hypomobile gall bladder?
gall bladder infection?
intravascular hemolysis?
hypomobile gallbladder=> biliary sludge
biliary infection => brown pigmented stones
intravascular hemolysis => black pigmented stones
what areas of the bowel are most susceptible to ischemia
watershed areas= splenic flexure (between SMA and IMA) and distal sigmoid (between IMA and hypogastric arteries)
what are the symptoms of Hepatitis A Virus infection
fever, dark urine (bilirubin), abdominal pain, N/V, malaise
what abnormal biopsy finding would you expect in a child with abetalipoproteinemia
accumulation of lipids in the enterocytes (due to inability to make chylomicrons since there is no B-48 or B-100)
what is the genetic defect (and inheritance) of abetalipoproteinemia
autosomal recessive mutation of MTP (microsomal triglyceride transfer protein) which normally serves as a chaperone for folding of ApoB and transfer of lipids to chylomicrons and VLDL particles
