37 Overview of GI

Question 1

4 layers of the GI tract?

Answer 1

Muocsa, Submucosa, Muscularis externa, Serosa

Question 2

3 layers of Mucosa?

Answer 2

1. epithelium (release GI hormone)
2. lamina propria (small blood vessels, nerve fibers, GALT: gut associated lymphoid tissue)
3. Muscularis mucosae

Question 3

2 layers of submucosa?

Answer 3

1. Submucosal nerve plexus

2. major blood vessels

Question 4

3 layers of muscularis externa?

Answer 4

1. circular muscle
2. myenteric nerve plexus (think muscle later controlling the movement of GI)
3. Longitudinal muscle

Question 5

2 components of GALT?

Answer 5

1. Peyer’s patches (lymphoid nodules) located at lamina propria (aggregates of lymphoid tissue, stationary lymphoid cells)
2. Intraepithelial lymphocytes (migrating, at mucosa/submucosa)

Question 6

What will GALT secrete in the lamina propria when there is over-activation like Chron’s disease/ Celiac disease?

Answer 6

Inflammatory mediators like cytokines and histamine

Question 7

Which of the function(s) is/are not regulated?
A. Digestion
B. Absorption
C. Secretion
D. Motility

Answer 7

A and B

C and D are finely subjected to neural and hormonal regulation

Question 8

Key locations of sphincters

Answer 8

LES (lower esophageal sphincter)
Pyloric sphincter 
Sphincter of Oddi (pancreas)
Ileocecal sphincter 
External anal sphincter