Lecture 6: Histology of the Esophagus and Stomach

Question 1

What are the four layers of the GI tract (lumen to superficial)?

Answer 1

mucosa > submucosa > muscularis externa > serosa adventitia

Question 2

3 components of the mucosal layer

Answer 2

lining epithelium (type varies)
lamina propia
muscularis mucosae

Question 3

What type of layer is the lamina propia and what is found here?

Answer 3

• vascularized loose Ct

- immune cells

Question 4

What is found in the submucosal layer

Answer 4

dense irregular CT layer

glands

Question 5

What is the muscularis externa?

What are the actions of both types of SM?

Answer 5

• 2 layers of SM (inner circular and outer longitudinal) with NV plexus sandwiched in between
• inner circular constricts, outer longitudinal shortens

Question 6

What is the difference between serosa and adventitia?

Answer 6

Serosa: superficial layer of the tract lined with mesothelium
Adventitia: superficial layer of the tract not lined with mesothelium

Question 7

Mucosal layers with protective function tend to have:

Mucosal layers with secretory function tend to have:

Answer 7

Nonkeratinized stratified squamous (mouth, throat, anus)

simple columnar epithelium (stomach)

Question 8

Mucosal layers with absorptive function tend to have:

Mucosal layers with absorptive and protective function tend to have:

Answer 8

simple columnar epithelium with crypts (less packed)

simple columnar epithelium with goblet cells and more closely packed

Question 9

What plexus of the ENS are present in the GI tract?

What is the role of the ENS in the GI tract?

Answer 9

Submucosal plexus of meissner
Myenteric plexus of Auerbach (between the two SMs)

regulate peristalsis and secretion by communicating with ANS

Question 10

What are the superficial layer does the esophagus have?

Answer 10

-both serosa (inferior to diaphragm) and adventitia (thoracic part)

Question 11

How is the epithelium lubricated?

Answer 11

cardiac esophageal glands and submucosal glands secrete mucus

Question 12

Characteristics of esophageal mucosa
Epithelium
Features

Answer 12

Nonkeratinized stratified squamous

lots of folds, has lamina propia over it

Question 13

Characteristics of esophageal submucosa
FEatures
Clinical significance?

Answer 13

• collagen and elastic fibers
• submucosal venous plexus drain into the systemic and portal venous system, increase in pressure here can cause esophageal varices

Question 14

Characterstics of esophageal muscularis externa:

Segmental muscle type transitions

Answer 14

Upper 1/3 of tract: striated skeletal muscle
Middle 2/3 of tract: skeletal and smooth
Lower 3/3 of tract: smooth muscle

Question 15

What histologically characterizes GERD?

Answer 15

esophageal layers become inflamed, ulcerated due to reflux of gastric contents
-nonkeratinized stratified squamous in transition zone becomes columnar (Barrett’s esophagus/metaplasia)

Question 16

How does the epithelium change at the gastroesophageal junction?

Answer 16

From non keratinized stratified squamous to simple columnar in the stomach (lots of glands)

Question 17

What are the differences in SM motility in the orad vs. caudad area of the stomach?

Answer 17

Orad area relaxes during swallowing

Cudad area contracts to empty the stomach

Question 18

What are rugae?

Answer 18

folds on the stomach epithelium that help with mechanical breakdown of food

Question 19

Characteristics of gastric mucosa:
Epithelium
Made of?

Answer 19

• simple columnar epithelium

- reticular and collagen fibers, secretions release facilitated by muscularis mucosae

Question 20

Characteristics of gastric submucosa:
type of CT?
contains?

Answer 20

-dense irregular CT

collagen, elastic fibers, vessels, lymphatics, meissner’s plexus

Question 21

Characteristics of gastric muscularis externa

Features?

Answer 21

-3 muscle layers (oblique, circular and longitudinal), circular thickens and forms the pyloric region

Question 22

Characteristics of the gastric serosa:
type of CT?
Contains?

Answer 22

• loose CT

- blood vessels

Question 23

What are fundic (gastric) glands?

What are the parts of the gastric glands?

Answer 23

branched glands at the muscularis mucosae layer of the gastric mucosa

gastric pit (surface), isthmus (narrow region in between), gastric gland

Question 24

What are surface mucous cells and mucous neck cells?

Answer 24

• line the lumen and gastric pits of the gland

- cells with round nuclei and apical granules found in the neck of the gland

Question 25

What is the significance of mucous cells?

Answer 25

mucus layer is 95% water and 5% mucin > forms insoluble gel on the mucosal surface > neutralizes acidic pH
-found in the gastric pit region

Question 26

Chief cells:
Found where?
Hallmarks?
Releases?

Answer 26

• neck of the gland
• lots of RER and apical granules that secrete zymogen
• pepsinogen (inactive pepsin) which digests proteins, gastric lipase which digests lipids

Question 27

Parietal cells:
Found where?
Hallmarks?
Releases?

Answer 27

• isthmus to parietal
• large round or pyramid shaped cells with lots of MT and eosinophilic cytoplasm, apical surface has intracelllular canaliculus with lots of microvilli
• HCl and intrinsice factor (B12 absorption)

Question 28

What are enteroendocrine cells?

Answer 28

cells on gastric epithelium that secrete various stuff

Question 29

Cardiac glands:
Found where?
Features?

Answer 29

• narrow region of stomach by the esophagus

- tubular, coiled and branced, appear circular and oblique in slide sections

Question 30

Pyloric Glands
Found where?
Hallmark:

Answer 30

• other end of the stomach (between fundus and pylorus)

- also tubular and coiled, has lymphoid cells (GALT) with immune function