GI Qbank

Question 1

What does urease convert urea to?

Answer 1

Carbon dioxide and ammonia, causing pH increase

Question 2

What supplements are used in breastfed infants?

Answer 2

Vitamin D and iron (in preterm/lower bw)

Question 3

What is seen on biopsy in celiac disease?

Answer 3

Villous atrophy, crypt hyperplasia, and intraepithelial lymphocyte infiltration

Question 4

What is the classic histologic finding in Whipple disease?

Answer 4

Small intestinal mucosa containing enlarged foamy macrophages packed with both rod shaped bacilli and PAS-positive, diastase resistant granules

Question 5

What is the most common clinical presentation of Whipple disease?

Answer 5

Middle-aged white males presenting as malabsorption with diarrhea and weight loss

Question 6

What is the gram stain of tropheryma whippelii?

Answer 6

Gram positive

Question 7

What cells produce secretin? Secretin is released in response to what?

Answer 7

Produces by duodenal S cells; released in response to increased duodena H+ concentrations

Question 8

What is the function of secretin?

Answer 8

Increase bicarb pancreatic secretion

Question 9

What is the embryological origin of the spleen?

Answer 9

Dorsal mesentery (mesoderm)

Question 10

What is the sudan III stain of the stool?

Answer 10

Qualitative assay that can identify unabsorbed fat and confirm malabsortion

Question 11

What is the rate limiting step of glycolysis?

Answer 11

PFK-1

Question 12

Cholesterol gallstones can be caused by inhibition of what enzyme?

Answer 12

7alpha hydroxylase

Question 13

Brown pigmented gallstones can be caused by what enzyme?

Answer 13

Beta-glucuronidase

Question 14

Brown pigmented gallstones are seen when?

Answer 14

Infection - esp E coli, A lumbricoides, C sinensis

Question 15

What are the different types of gallstones? When do you see each?

Answer 15

Pigmented (brown = infection; black = hemolysis); cholesterol

Question 16

What are pigmented gallstones composed of?

Answer 16

Calcium salts of uncojugated bilirubin

Question 17

What is the function of beta-glucuronidase?

Answer 17

Released by injured hepatocytes and bacteria in pigmented gallstones; hydrolyzes bilirubin glucuronides and increased amount of unconjugated bilirubin

Question 18

What toxin is associated with bacillus anthracis? Factors?

Answer 18

Anthrax exotoxin - edema factor and lethal factor

Question 19

What is the mechanism of edema factor seen in B anthracis?

Answer 19

Acts as adenylyl cyclase and increased cAMP

Question 20

What is the mechanism of lethal factor in B anthracis?

Answer 20

Protease that inhibits protein kinase signaling, causing apoptosis

Question 21

What is the mechanism of pertussis toxin?

Answer 21

ADP ribosylation of Gi, disinhibiting adneylate cyclase, increasing cAMP levels, causing edema and phagocyte dysfunction

Question 22

What is the mechanism of botulinum toxin?

Answer 22

Blocks presynaptic release ACh resulting in flaccid paralysis

Question 23

What toxins does C diff have?

Answer 23

Toxin A and toxin B

Question 24

What is the mechanism of toxin A seen in C. Diff?

Answer 24

Recruits and activates neutrophils, leading to release of cytokines that cause mucosal inflammation and fluid loss, diarrhea

Question 25

What is the mechanism of toxin B of C diff?

Answer 25

Induces actin depolymerization, leading to mucsoal cell death, bowel wall necrosis, pseudomembrane formation

Question 26

What is the mechanism of shiga toxin?

Answer 26

ADP ribosylation; disables 60s ribosomal subunit by removing adenine form rRNA; leading to intestinal epithelial cell death and diarrhea

Question 27

What strain of E coli does not ferment sorbitol overnight?

Answer 27

EHEC O157:H7

Question 28

What is the mechanism of shiga-like toxin?

Answer 28

Inactivates 60s ribosomal subunit

Question 29

What is the characteristic pathology seen in primary biliary cholangitis?

Answer 29

Lymphocytic infiltrates and destruction of small and mid-sized intrahepatic bile ducts; can see granulomas

Question 30

In GVHD, what organs are most commonly affected?

Answer 30

Skin, liver, gastrointestinal

Question 31

What is seen histologically in GVHD?

Answer 31

Lymphocytic infiltration and destruction of small intrahepatic bile ducts

Question 32

What pathology is seen in acetaminophen OD?

Answer 32

Liver failure with centrilobular necrosis

Question 33

What pathology is seen in alcoholic hepatitis?

Answer 33

Hepatocellular swelling and necrosis, mallory bodies, and neutrophilic infiltration and fibrosis

Question 34

What are the endoscopic findings on HSV-1 esophagitis?

Answer 34

Small vesicles resulting in punched-out ulcers

Question 35

What endoscopic findings are seen in CMV esophagitis?

Answer 35

Linear ulcerations

Question 36

What are the endoscopic findings of candida albicans esophagitis?

Answer 36

Patches of adherent, grey/white pseudomembranes on erythematous mucosa

Question 37

What is the most common cause of duodenal PUD?

Answer 37

H pylori

Question 38

Wht is Kehr sign?

Answer 38

Shoulder pain representing referred pain de to peritoneal irritation

Question 39

What is the sensory innervation of internal hemorrhoids?

Answer 39

Autonomic from the inferior hypogastric plexus

Question 40

What is the innervation of external hemorrhoids?

Answer 40

Branches of pudendal nerves

Question 41

Where is iron absorbed in the GI tract?

Answer 41

Duodenum and proximal jejunum