Gut Histology

Question 1

What are the 4 layers in the general structure of the gut?

Answer 1

Mucosa
Submucosa
Muscularis
Adventitia

Question 2

What is the deepest layer in gut histology?

Answer 2

Mucosa

Question 3

What does the mucosa of the gut made up of?

Answer 3

Epithelium layer

Lamina propria layer- containing blood vessels, lymphatics, and immune cells

Question 4

What layer of the gut is superficial to the mucosa?

Answer 4

Submucosa

Question 5

What is the submucosa of the gut made up of?

Answer 5

Made up of fibroblasts,collagen, and an extracellular matrix
Contains vessels, lymphatic tissue, nerves, glands

Question 6

What layer of the gut is superficial to the submucosa?

Answer 6

Muscularis externa

Question 7

What is muscularis externa made up of?

Answer 7

2-3 Layers of smooth muscle

• Circular muscle, longitudinal muscle and nerves
• responsible for the peristalsis of the gut

Question 8

What is peristalsis?

Answer 8

Rhythmic contractions of the gut to push food through the digestive system

Question 9

What is the most superficial layer to the gut?

Answer 9

Adventitia/serosa

Question 10

What is the adventitia/serosa of the gut made up of?

Answer 10

Outer layer of fibroblasts,collagen and some adipocytes

Question 11

What type of epithelium lines the oesophagus?

Answer 11

Stratified squamous epithelium

Question 12

How does the epithelium structure of the eosophagus relate to its function?

Answer 12

This type of epithelium protects against friction from passing food by shedding the layers closest to the lumen

Question 13

What is the function of the external muscle layer of the gut?

Answer 13

The muscle layers work together to produce peristalsis and move food along the oesophagus to the stomach

Question 14

What type of muscle is found in the muscularis externa of the oesophagus wall?

Answer 14

Superior 1/3-skeletal muscle
Middle 1/3- mix of skeletal and smooth muscle
Inferior 1/3-smooth muscle

Question 15

How does the epithelium change at the gastro-oesophageal junction?

Answer 15

Sharp transition from stratified squamous epithelium to columnar epithelium

Question 16

What is the clinical significnace of the change in epithelium at the gastro-oesophageal junction?

Answer 16

Risk of disease due to exposure of a cell type to an environment that it is not suited for e.g stratified squamous epithelium exposed to stomach acid

Question 17

What type of epithelium is found in the stomach? What doe these cells secrete and what is the function of this?

Answer 17

• Simple columnar epithelium

- Secretes mucus to pretect the epithelial lining from autodigestion ( being digested by the stomach acid)

Question 18

What is the name given to the folds within the stomach and what is the function of these folds?

Answer 18

Gastric fold or rugae

-allows for the expansion of the stomach after consumption of foods and liquids

Question 19

What are the crypts of lieberkukn?

Answer 19

Tubular glands which are found between the villi

-many important cells reside in the crypts such as stem cell that replenish the epithelial cells further up the villi

Question 20

Where are the crypts of lieberkukn found?

Answer 20

Located between the villi and intestinal epithelium

Question 21

What are Brunner glands?

Answer 21

Glands that secrete an alkalie fluid into the duodeum to protect it from the acid chyme of the stomach

Question 22

What layer of gut histology are the brunner glands found?

Answer 22

Located in the mucosa

Question 23

What are Peyer’s patches?

Answer 23

Small masses of lymphatic tissue found throughout the ileum. Important in immune surveillance

Question 24

What layer of gut histology are the Peyer’s patches found?

Answer 24

Located in the mucosa and extend into the submucosa

Question 25

What is the functional significance of villi?

Answer 25

Increase surface area to maximize the rate of absorption

Question 26

What type of epithlial is present in the small intestine?

Answer 26

Columnar absorptive epithelium

Question 27

What is the brush border of the small intestine and what is its function?

Answer 27

Brush border is composed of microvilli, which increase surface area for absorption

Question 28

Compare the structures present in the duodenum, jejunum and iluem

Answer 28

• All have villi and crypts of leiberkukn between them
• Duodenum is identified by the presence of brunner glands
• Ileum is identified by the presence of Peyer’s patches
• Jejunum is idenified by the absense of both the brunner glands and Peyer’s patches

Question 29

What is the function of goblet cells in the large intetsine?

Answer 29

They secrete mucus to lubricate passage of increasingly solid gut contents

Question 30

How does the histology of the large intestine differ from the small intestine?

Answer 30

In the large intestine:

• No villi or brush border
• Crypts are straigter and more densely packed with goblet cells
• Longitudinal muscle more discontinuous, arranged as 3 strips along the colon

Question 31

What is the pectinate line?

Answer 31

A line that indicates the recto-anal junction

Question 32

What hapens to the intestinal epithelial at the recto-anal junction?

Answer 32

Sudden change from columnar epithelium to stratified squamous epithelium (becomes keratinized after a few millimeters)