Histopathology And Cellular Function ✅

Question 1

Describe the structure of the GI tract, from mouth to anus?

Answer 1

Tubular structure with 4 layers

Question 2

What are the layers of the GI tract?

Answer 2

• Mucosa
• Submucosa
• Muscularis externa
• Serosa

Question 3

What is the mucosa of the GI tract made up of?

Answer 3

• Epithelium
• Connective tissue
• Thin smooth muscle

Question 4

What is the submucosa of the GI tract made up of?

Answer 4

Connective and supportive tissue

Question 5

What is the muscularis externa of the GI tract made up of?

Answer 5

Two thick layers of smooth muscle

Question 6

What is the serosa of the GI tract made up of?

Answer 6

Thin outer layer of connective and supportive tissue

Question 7

What epithelium does the oesophagus have?

Answer 7

Non-keratinised stratified squamous epithelium

Question 8

What is the function of the muscularis externa in the oesophagus?

Answer 8

Peristaltic contractions of the muscuarlis externa propel the food boluses forward into the stomach

Question 9

What epithelium is present in the stomach?

Answer 9

Columnar epithelium

Question 10

What does the columnar epithelium of the stomach contain?

Answer 10

• Mucus-secreting cells

- Many immune cells

Question 11

What do the mucus secreting cells in the stomach mucosa form?

Answer 11

Gastric pits

Question 12

How do the mucus secreting cells in the gastric mucosa form gastric pits?

Answer 12

By invaginating down

Question 13

What happens to the gastric pits from the fundus to the pylorus?

Answer 13

They become deeper

Question 14

What immune cells are present in the gastric mucosa?

Answer 14

• Plasma cells

- Lymphocytes

Question 15

What is the inner lining of the small intestine formed of?

Answer 15

• Plicae circularis
• Villi
• Mucosal epithelium

Question 16

What are plicae cirecularis?

Answer 16

Transverse ridges

Question 17

What are villi?

Answer 17

Tall finger-like projections of mucosa

Question 18

What is found between the villi in the small intestine?

Answer 18

Crypts of Lieberkuhn

Question 19

What kind of epithelium is found in the small intestine?

Answer 19

Columnar

Question 20

What is the function of microvilli in the small intestine?

Answer 20

They greatly increase the surface area

Question 21

What is the surface area of the small intestine in adults?

Answer 21

250m2

Question 22

How can the duodenum be distinguished histologically?

Answer 22

By presence of Brunner’s cells

Question 23

Where are Brunner’s cells found?

Answer 23

At the hepato-pancreatic sphincter (sphincter of Oddi)

Question 24

What is the function of Brunner’s cells?

Answer 24

They produce an alkaline substance to aid digestion

Question 25

Which portion of the small intestine has the tallest villi?

Answer 25

Jejenum

Question 26

Where do the villi extent from in the jejunum?

Answer 26

The permanent circular fold of the mucosa and submucosa

Question 27

How is the ileum identified histologically?

Answer 27

Presence of aggregated lymphoid follicles, known as Peyer’s patches, which are found in the submucosa

Question 28

What is the predominant immune cell found throughout the GI system?

Answer 28

Lymphocytes

Question 29

Where are lymphocytes found in the GI tract?

Answer 29

In the surface epithelium and in the lymphoid follicles

Question 30

What do the lymphocytes found in the GI tract collectively make up?

Answer 30

Gut-associated lymphoid tissue (GALT)

Question 31

What other immune-mediating cells are found in the small intestine?

Answer 31

Paneth cells

Question 32

Where are Paneth cells located?

Answer 32

In the crypts

Question 33

What do Paneth cells contain?

Answer 33

Granular material important in lysis of microorganisms

Question 34

What is present in the colon when viewed microscopically?

Answer 34

A number of microscopic crypts that extend down to the muscularis mucosa

Question 35

What is found within the crypts of the colon?

Answer 35

Goblet cells

Question 36

What is the function of the goblet cells of the colon?

Answer 36

Production of mucus

Question 37

What GI abnormalities can be diagnosed with histopathology?

Answer 37

- Coeliac disease - Inflammatory bowel disease - Eosinophilic diseases - Oesophagitis, gastritis, and gastro-oesophageal reflux

Question 38

What is coeliac disease?

Answer 38

A multi-system disease, including a small intestinal enteropathy secondary to exposure to gluten

Question 39

What are the classic histological findings of coeliac disease?

Answer 39

- Flattened duodenal mucosa with loss of crypt architecture - Intraepithelial lymphocytosis - Glandular hyperplasia

Question 40

Are the histological findings in coeliac disease reversible?

Answer 40

Yes

Question 41

How can the histological findings in coeliac disease be reversed?

Answer 41

Gluten exclusion diet

Question 42

Where can changes be demonstrated histologically in Crohn’s disease?

Answer 42

Anywhere from mouth to anus

Question 43

What is found histologically in Crohn’s disease?

Answer 43

- Areas of chronic inflammation, comprising increased lamina propria plasma cells and lymphocytes - Skip lesions including patchy erosions or ulcers, vertical fissures, and fistulas - Transmural inflammation with multiple lymphoid aggregates and granulomas

Question 44

Where does UC affect?

Answer 44

Only the large bowel

Question 45

What is found histologically in UC?

Answer 45

- Alteration of crypt architecture, including cryptitis and crypt abscesses - Increased chronic inflammatory cells in the lamina propria, including lymphocytes and plasma cells

Question 46

Are eosinophils normally found in the GI tract?

Answer 46

Yes

Question 47

What happens in eosinophilic disease of the GI tract?

Answer 47

There is a markedly increased eosinophilic infiltrate in the mucosa

Question 48

What do the symptoms of eosinophilic diseases of the GI tract depend on?

Answer 48

The site of the disease

Question 49

How does eosinophilic oesophagitis present?

Answer 49

- Dysphagia - Retrosternal chest pain - Bolus dysphagia (food bolus lodged in oesophagus)

Question 50

How does eosinophilic intestinal disease present?

Answer 50

- Recurrent abdominal (often epigastric) pain - Vomiting - Dysphagia - Diarrhoea

Question 51

When can inflammation of the oesophagus and stomach occur?

Answer 51

When there is excess secretion of gastric acid, and if the contents of the stomach reflux back into the oesophagus

Question 52

Who is gastro-oesophageal reflux common in?

Answer 52

Infants

Question 53

Why is gastro-oesophageal reflux common in infants?

Answer 53

Due to the immaturity of the lower oesophageal sphincter

Question 54

How does gastro-oesophageal reflux differ in infants compared to adults?

Answer 54

In infants, it is rarely associated with the formation of dysplastic cells, such as those seen in Barrett’s oesophagus in adults

Question 55

What are the other causes of oesophageal and gastric inflammation?

Answer 55

- Ingestion of caustic material - Presence of H. Pylori - General severe systemic illness such as sepsis