Histology of the Gut

Question 1

What are the 4 layers of the oesophagus?

Answer 1

Mucosa
Submucosa
Muscularis propria
Adventitia

Question 2

Functions of sublayers of Muscosa? Oes

Answer 2

Epithelium - Protection, mucous production
Lamina Propia - capillary rich, absorption, MALT (infection protection)
Muscularis Mucosa - localized movements, contractions

Question 3

Functions of submucosa? Oes

Answer 3

Highly vascularized - enhances nutrient absorption
Lubrication for passage of bolus
Contains submucosal (Meissner) nerve plexus - controlling muscle cells and glandular secretion

Question 4

Features of oesophagus lumen? Oes

Answer 4

2 layers
Inner circular layer of muscular external
Longitudinal layer of muscular external

Peristaltic activity

Question 5

What does the myenteric plexus do?

Answer 5

Controls and generates contractions of the musclaris

Question 6

Features of adventitia? Oes

Answer 6

Loose connective tissue

Question 7

What is the adventitia called after it passes the diaphragm?

Answer 7

Serosa

Question 8

What type of epithelium lines the oesophagus?

Answer 8

Stratified squamous non-keratinized epithelium

Question 9

What other cell can be found in the mucosa lining the lumen of the oesophagus?

Answer 9

Langerhans cells - phagocytose and degrade antigens

Question 10

Explain Barret’s oesophagus?

Answer 10

Acid reflux from the stomach damages the lining of the oesophagus

Question 11

What type of epithelium lines the stomach?

Answer 11

Simple columnar epithelium

Question 12

Why is more mucus found in the Pylorus and Cardia of the stomach?

Answer 12

For neutralisation of the acidic conditions

Question 13

What does the combination of HCL + Pepsinogen produce and why is it useful?

Answer 13

Pepsin to digest proteins

Question 14

What are the types of cells (and roles) in the stomach?

Answer 14

Surface lining cells
Regenerative cells - replace cells
Mucous neck cell - mucous
Oxyntic (parietal) cell - HCL, intrinsic factor (B12)
Zymogenic (chief) cell - gastric lipase, pepsinogen
Enteroendocrine cell - gastrin for HCL release

Question 15

What is intrinsic factor and what clinical issue presents in people who do not have one?

Answer 15

A secretion that aids in B12 absorption

No factor - pernicious anemia

Question 16

What is the mucosa of the SI composed of?

Answer 16

Simple columnar epithelium
Lamina propria
Muscularis mucosae

Question 17

What do Paneth cells do and where are they found?

Answer 17

Protect from ingested microbes

Found in crypts of Lieberkuhn

Question 18

Where are Brunner’s glands found and what is their role?

Answer 18

Secrete mucous that neutralizes the acidic chyme

Duodenum

Question 19

Where are the crypts of Lieberkuhn and what is their role?

Answer 19

Duodenum, Jejunum, Ileum, Colon, Rectum

Question 20

What cells (and their roles) are found in the Ileum?

Answer 20

Goblet cells - mucous (neutralisation)
Villus core - microvasculature, lymphatics
Peyer’s patches - lymphoid follicles (infection)

Question 21

Go through the SI segments in decreasing length of villi.

Answer 21

Duodenum, jejunum, ileum

Question 22

Describe the features of the LI

Answer 22

Simple columnar epithelium
No Paneth cells
Taeniae coli - movement

Question 23

What is MALT and what does it do?

Answer 23

Mucosa Associated Lymphoid Tissue, protects against invaders of the mucosal connective tissue

Question 24

What is the epithelium lining of the rectum?

Answer 24

Simple columnar epithelium

Question 25

How does the lining of the epithelium change in the anal canal?

Answer 25

Stratified squamous epithelium