Histology

Question 1

What are the four layers of the GIT?

Answer 1

Mucosa
Submucosa
Muscularis propria
Adventitia (serosa)

Question 2

What are the three layers of mucosa in the GIT?

Answer 2

Epithelium, lamina propria and muscularis mucosae

Question 3

What is the submucosa made of and what does it contain?

Answer 3

Mase of loose collagenous tissue containing blood vessels, lymphatics, nerve submucosal plexus and lymphoid aggregates

Question 4

What are the two layers of the muscularis propria and what lies between them?

Answer 4

Inner circular muscle and outer longitudinal

The myenteric plexus lies between these two layers

Question 5

When do you have adventitia and serosa and what is it comprised of?

Answer 5

Sersoa when intraperitoneal and adventitia when retroperitoneal
It is an outer layer of loose supporting tissue conducting major vessels, nerves and contains variable amounts of adipose tissue.

Question 6

What lines the oesophagus?

Answer 6

Stratified squamous epithelium

Question 7

What occurs in Barretts oesophagus?

Answer 7

There is metaplasia (change in cell type) from stratified squamous to columnar epithelium which is usually found in the intestine. occurs in response to acid reflux

Question 8

What occurs at the gastro-oesophageal junction?

Answer 8

Change from stratified squamous epithelium to simple columnar

Question 9

What is the role of surface mucous cells?

Answer 9

Secrete bicarbonate to protect the epithelium from acidic gastric juices

Question 10

What is the role of parietal cells?

Answer 10

secrete gastric acid and intrinsic factor

Question 11

What is the role of chief cells?

Answer 11

secrete pepsin

Question 12

What is the distinguishing feature of the muscularis propria in the stomach?

Answer 12

There is an additional layer of muscle (inner oblique)

Question 13

What can helicobacter pylori cause?

Answer 13

gastritis, adenocarcinoma, lymphoma and gastric ulcers

Question 14

What occurs at the gastro-duodenal junction

Answer 14

change from simple columnar epithelium to villous mucosa lined by columnar mucosa with goblet cells

Question 15

What is the function of the villi and what are the spaces in-between them called

Answer 15

Increase the surface area for absorption

In-between there are the crypts of Lieberkuhn which extend down to the muscularis mucosae

Question 16

What is the feature unique to the duodenum?

Answer 16

Brunners glands in the submucosa that secrete a thin alkaline mucus in response to chyme that will protect the duodenal mucosa from auto digestion

Question 17

what does chyme stimulate?

Answer 17

Brunners glands and release of CCK and secretin from neuroendocrine cells which will stimulate pancreatic secretions and gallbladder contractions

Question 18

What are enterocytes?

Answer 18

Absorptive cells with microvilli that line the villi and crypts

Question 19

What is the role of goblet cells?

Answer 19

to produce mucin for lubrication and protection - scatted amongst the enterocytes

Question 20

what are paneth cells, where are they found and what is their function?

Answer 20

Found at the base of the crypts and are distinguished by their prominent eosinophilic apical granules - defensive function

Question 21

Where are the stem cells found?

Answer 21

at the base of the crypts and can divide to form all 4 cell types

Question 22

What occurs at the ileo-caecal junction?

Answer 22

change from villous mucosa to simple columnar which forms tubular glands (crypts)

Question 23

What are the two cell types in the large intestine?

Answer 23

Goblet cells

Absorptive cells

Question 24

What are the differences between small and large intestine?

Answer 24

Small: finger like villi and crypts (not as many goblet cells)
Large: deep crypts without villi (lots of goblet cells)

Question 25

What occurs at the recto-anal junction

Answer 25

change from glandular mucosa to stratified squamous

Question 26

What are the four junctions which have a distinct change in mucosa?

Answer 26

oesophageal-gastric
gastro-duodenal
ileo-ceacal
Recto-anal