GI Qbank Flashcards
What does urease convert urea to?
Carbon dioxide and ammonia, causing pH increase
What supplements are used in breastfed infants?
Vitamin D and iron (in preterm/lower bw)
What is seen on biopsy in celiac disease?
Villous atrophy, crypt hyperplasia, and intraepithelial lymphocyte infiltration
What is the classic histologic finding in Whipple disease?
Small intestinal mucosa containing enlarged foamy macrophages packed with both rod shaped bacilli and PAS-positive, diastase resistant granules
What is the most common clinical presentation of Whipple disease?
Middle-aged white males presenting as malabsorption with diarrhea and weight loss
What is the gram stain of tropheryma whippelii?
Gram positive
What cells produce secretin? Secretin is released in response to what?
Produces by duodenal S cells; released in response to increased duodena H+ concentrations
What is the function of secretin?
Increase bicarb pancreatic secretion
What is the embryological origin of the spleen?
Dorsal mesentery (mesoderm)
What is the sudan III stain of the stool?
Qualitative assay that can identify unabsorbed fat and confirm malabsortion
What is the rate limiting step of glycolysis?
PFK-1
Cholesterol gallstones can be caused by inhibition of what enzyme?
7alpha hydroxylase
Brown pigmented gallstones can be caused by what enzyme?
Beta-glucuronidase
Brown pigmented gallstones are seen when?
Infection - esp E coli, A lumbricoides, C sinensis
What are the different types of gallstones? When do you see each?
Pigmented (brown = infection; black = hemolysis); cholesterol
What are pigmented gallstones composed of?
Calcium salts of uncojugated bilirubin
What is the function of beta-glucuronidase?
Released by injured hepatocytes and bacteria in pigmented gallstones; hydrolyzes bilirubin glucuronides and increased amount of unconjugated bilirubin
What toxin is associated with bacillus anthracis? Factors?
Anthrax exotoxin - edema factor and lethal factor
What is the mechanism of edema factor seen in B anthracis?
Acts as adenylyl cyclase and increased cAMP
What is the mechanism of lethal factor in B anthracis?
Protease that inhibits protein kinase signaling, causing apoptosis
What is the mechanism of pertussis toxin?
ADP ribosylation of Gi, disinhibiting adneylate cyclase, increasing cAMP levels, causing edema and phagocyte dysfunction
What is the mechanism of botulinum toxin?
Blocks presynaptic release ACh resulting in flaccid paralysis
What toxins does C diff have?
Toxin A and toxin B
What is the mechanism of toxin A seen in C. Diff?
Recruits and activates neutrophils, leading to release of cytokines that cause mucosal inflammation and fluid loss, diarrhea
What is the mechanism of toxin B of C diff?
Induces actin depolymerization, leading to mucsoal cell death, bowel wall necrosis, pseudomembrane formation
What is the mechanism of shiga toxin?
ADP ribosylation; disables 60s ribosomal subunit by removing adenine form rRNA; leading to intestinal epithelial cell death and diarrhea
What strain of E coli does not ferment sorbitol overnight?
EHEC O157:H7
What is the mechanism of shiga-like toxin?
Inactivates 60s ribosomal subunit
What is the characteristic pathology seen in primary biliary cholangitis?
Lymphocytic infiltrates and destruction of small and mid-sized intrahepatic bile ducts; can see granulomas
In GVHD, what organs are most commonly affected?
Skin, liver, gastrointestinal
What is seen histologically in GVHD?
Lymphocytic infiltration and destruction of small intrahepatic bile ducts
What pathology is seen in acetaminophen OD?
Liver failure with centrilobular necrosis
What pathology is seen in alcoholic hepatitis?
Hepatocellular swelling and necrosis, mallory bodies, and neutrophilic infiltration and fibrosis
What are the endoscopic findings on HSV-1 esophagitis?
Small vesicles resulting in punched-out ulcers
What endoscopic findings are seen in CMV esophagitis?
Linear ulcerations
What are the endoscopic findings of candida albicans esophagitis?
Patches of adherent, grey/white pseudomembranes on erythematous mucosa
What is the most common cause of duodenal PUD?
H pylori
Wht is Kehr sign?
Shoulder pain representing referred pain de to peritoneal irritation
What is the sensory innervation of internal hemorrhoids?
Autonomic from the inferior hypogastric plexus
What is the innervation of external hemorrhoids?
Branches of pudendal nerves
Where is iron absorbed in the GI tract?
Duodenum and proximal jejunum
