Gastroduodenal Mucosal Protection, Ulcers

Question 1

what’s the most important function of GI tract?

Answer 1

ability to regulate trafficking of macromolecules between environment and host through barrier mechanism

Question 2

functions of GI barrier

Answer 2

efficient transport of nutrients
protect epithelial cells

Question 3

list GI barrier components

Answer 3

osmotic permeability
stem cells - support repair
bicarb microclimate adjacent for H gradient
mucus gel layer
immune defense

Question 4

list the three components of mucosal barrier

Answer 4

tight junctions
mucus layer
immune cells

Question 5

what makes the microenvironment separating lumen and apical membrane?

Answer 5

glycocalyx
mucus
unstirred water

Question 6

___ cells secrete layer of mucus

Answer 6

goblet

Question 7

where in GI is the mucus layer thickest?

Answer 7

colon

Question 8

mucus layer consists of ___.

Answer 8

mucin

Question 9

is the mucus gel layer static?

Answer 9

NO
abrasion can remove pieces
low pH cases sloughing

Question 10

what triggers mucus secretion?

Answer 10

vagal stim
physical/chemical irritation

Question 11

what creates a neutral character of mucus gel layer?

Answer 11

unstirred water and bicarb secretion
bicarb remains in mucus gel
PGE2 stim bicarb secretion, inhibits gastric acids

Question 12

what are paneth cells?

Answer 12

granulocytes in SI crypt

Question 13

what are peyers patches?

Answer 13

lymphatic tissue masses in SI (ileum)

Question 14

what are the two types of PRR’s in GI?

Answer 14

TLR
NOD-like receptor aka NLR

Question 15

what do paneth cells synthesize and secrete?

Answer 15

antimicrobial peptides
alpha-defensins aka cryptdins

Question 16

how do commensal bacteria provide protection?

Answer 16

inhibitory compounds
compete for adhesion sites
modulate response

Question 17

what is inflammatory bowel disease?

Answer 17

chronic inflammation of GI tract
breakdown of regulatory mechanisms that cooperate to maintain GI homeostasis
**excessive normal function

Question 18

describe how IBD is a multifactorial disease?

Answer 18

Question 19

what are two disruptions of GI barrier?

Answer 19

toxicity of NSAID/heliobacter/parasites
ischemia

Question 20

how are epithelial cells qucikly repaired?

Answer 20

stem cells in neck of crypts

Question 21

what are ulcers?

Answer 21

disruption to mucosal integrity
excessive exposure to acid

Question 22

what are two causes of excess acid exposure (causing ulcers)?

Answer 22

1. caused by excess gastric acid production
2. caused by damage to mucus gel layer while acid production stays normal

Question 23

PG are quickly synthesized by…

Answer 23

COX path

Question 24

NSAID ____ COX pathway

Answer 24

inhibit

Question 25

NSAID toxicity effects on the following…
mucus
bicarb
blood flow
cell restitution
inflammation

Answer 25

Question 26

how can NSAIDs become trapped in epithelial cells?

Answer 26

neutral pH of inner cell lumen causes trap in ionized form

Question 27

what are aspirin side effects?

Answer 27

V, D, mucosal erosion, ulcer, black stool

Question 28

aspirin overdose signs

Answer 28

V, D, appetite loss, acid/base issue, seizure, coma, dead

Question 29

what is heliobacter pylori?

Answer 29

gram negative bacteria
infection linked to gastritis, peptic ulcer, higher gastric neoplasia rate

Question 30

what does helicobacter pylori do to its flagella, and pH?

Answer 30

burrows flagella into mucus layer, increases pH

Question 31

the presence of parasites in GI causes…

Answer 31

1. mechanical damage to mucus layer and mucosa
2. chronic exposure to acidic environment
3. inability to repair cells

Question 32

two types of GI ischemia

Answer 32

non-occlusive
occlusive

Question 33

what is occlusive ischemia?

Answer 33

directly disrupt GI blood flow

Question 34

what is non-occlusive ischemia?

Answer 34

due to reduced capillary blood flow or shunting away from GI tract
ex: stress, cushings