B5.032 Prework 1 Gastric Ulcers

Question 1

definition of gastric ulcer

Answer 1

5 mm or greater break in the lining of the stomach that extends into the submucosa on biopsies or has an appreciable depth during upper endoscopy

Question 2

how does pepsin play a role in causing gastric ulcers

Answer 2

enzyme active at acidic pH

pepsin can digest proteins within ulcer base and grow ulcer

Question 3

epidemiology of gastric ulcers

Answer 3

0.14-0.19% annual incidence in US
17-22% in China (H.pylori more prevalent)
incidence inclines with improvements in sanitation

Question 4

major complications of ulcers

Answer 4

GI bleeding (0.02-0.006% incidence)
perforation (0.004-0.014% incidence)
overall:
bleeding in 10% of ulcer, perforation in 1%

Question 5

why is acid a necessary component of the digestive system?

Answer 5

acid helps with protein digestion by converting pepsinogen to pepsin
promotes absorption of nonheme iron, vitamin B12, and meds such as ketoconazole and thyroxine
prevent bacterial overgrowth

Question 6

parietal cell

Answer 6

main cell that makes acid

Question 7

gastrin

Answer 7

main hormone produced by antral G cells to stimulate parietal cells to secrete acid

Question 8

somatostatin

Answer 8

main inhibitor of acid secretion

Question 9

vagus nerve/ Ach

Answer 9

main neurotransmitter that regulates acid secretion by modulating the secretion of gastrin, somatostatin and histamine

Question 10

H+K+ATPase

Answer 10

final common pathway from acid secretion from all stimuli

Question 11

how is H+ secreted

Answer 11

occurs in exchange for uptake of K+ ions to maintain neutral electric charge inside the cell
K+ in gastric juice exceeds plasma K+ 2-4 fold

Question 12

main defenses against gastric ulcer

Answer 12

mucus secretion
bicarb secretion
pH gradient across epithelial surface into lumen

Question 13

mucus secretion as a defense against acid

Answer 13

firm adherent viscous layer that covers the gastric surface
composed of 95% water and 5% cross linked mucin glycoproteins that are produced by MUC genes
prostaglandin secretion promotes mucus secretion

Question 14

major causes of ulcers

Answer 14

H. pylori
NSAIDs
idiopathic
Zollinger Ellison

Question 15

discuss H.pylori infections

Answer 15

majority of people have pangastritis involving both antral and fundic mucosa that lowers stomach defenses by reducing mucous protection
minority of patients have an antrum predominant gastritis which results in high gastric acid secretion (major mechanism of duodenal ulcer formation)

Question 16

clinical presentation of ulcers

Answer 16

epigastric pain
periodicity (every 6-12 weeks)
some older patients may not develop ab pain and present with bleeding or perforation

Question 17

diagnosis of ulcers

Answer 17

EGD is procedure of choice for uncomplicated

CT scan is the diagnostic modality of choice for perforated ulcers

Question 18

special considerations about ulcer causes

Answer 18

type A personality is a risk factor
combo of steroids + NSAID increases risk 8 fold
HP proportion declining, but idiopathic is growing (20-30% in US are idiopathic)

Question 19

treatment of gastric ulcers

Answer 19

mainstay is medical management

Question 20

types of medical management for gastric ulcers

Answer 20

treat HP or remove offending NSAID agent
antacids only 67% effective
anti secretory agents to reduce acid production
mucosal protective agents

Question 21

types of anti secretory agents

Answer 21

H2 blockers

proton pump inhibitors

Question 22

types of mucosal protective agents

Answer 22

sucralfate
pepto bismol
misoprostol

Question 23

H2 blockers

Answer 23

competitive inhibitors of histamine stimulated acid secretion and markedly suppress acid secretion

Question 24

PPIs

Answer 24

inhibit H+K+ATPase
final common pathway
“big guns” for acid suppression
pro-drugs and must be activated by acid

Question 25

sucralfate

Answer 25

ulcer exposes positively charged proteins which can bind to the sulfate anions in sucralfate
covers the surface of the ulcer and prevents further damage

Question 26

pepto bismol

Answer 26

can form complexes with mucus to coat ulcers
also has activity against HP infection
turns stools black
colonic bacteria convert bismuth salts to bismuth sulfide that turns stool black

Question 27

misoprostol

Answer 27

PGE analog which can enhance mucosal defense mechanisms and also inhibit gastric secretion through inhibition of histamine stimulated cyclic AMP pathway

Question 28

refractory gastric ulcers

Answer 28

most heal within 8 weeks