Lecture 6: Histology of the Esophagus and Stomach Flashcards
(30 cards)
What are the four layers of the GI tract (lumen to superficial)?
mucosa > submucosa > muscularis externa > serosa adventitia
3 components of the mucosal layer
lining epithelium (type varies)
lamina propia
muscularis mucosae
What type of layer is the lamina propia and what is found here?
- vascularized loose Ct
- immune cells
What is found in the submucosal layer
dense irregular CT layer
glands
What is the muscularis externa?
What are the actions of both types of SM?
- 2 layers of SM (inner circular and outer longitudinal) with NV plexus sandwiched in between
- inner circular constricts, outer longitudinal shortens
What is the difference between serosa and adventitia?
Serosa: superficial layer of the tract lined with mesothelium
Adventitia: superficial layer of the tract not lined with mesothelium
Mucosal layers with protective function tend to have:
Mucosal layers with secretory function tend to have:
Nonkeratinized stratified squamous (mouth, throat, anus)
simple columnar epithelium (stomach)
Mucosal layers with absorptive function tend to have:
Mucosal layers with absorptive and protective function tend to have:
simple columnar epithelium with crypts (less packed)
simple columnar epithelium with goblet cells and more closely packed
What plexus of the ENS are present in the GI tract?
What is the role of the ENS in the GI tract?
Submucosal plexus of meissner
Myenteric plexus of Auerbach (between the two SMs)
regulate peristalsis and secretion by communicating with ANS
What are the superficial layer does the esophagus have?
-both serosa (inferior to diaphragm) and adventitia (thoracic part)
How is the epithelium lubricated?
cardiac esophageal glands and submucosal glands secrete mucus
Characteristics of esophageal mucosa
Epithelium
Features
Nonkeratinized stratified squamous
lots of folds, has lamina propia over it
Characteristics of esophageal submucosa
FEatures
Clinical significance?
- collagen and elastic fibers
- submucosal venous plexus drain into the systemic and portal venous system, increase in pressure here can cause esophageal varices
Characterstics of esophageal muscularis externa:
Segmental muscle type transitions
Upper 1/3 of tract: striated skeletal muscle
Middle 2/3 of tract: skeletal and smooth
Lower 3/3 of tract: smooth muscle
What histologically characterizes GERD?
esophageal layers become inflamed, ulcerated due to reflux of gastric contents
-nonkeratinized stratified squamous in transition zone becomes columnar (Barrett’s esophagus/metaplasia)
How does the epithelium change at the gastroesophageal junction?
From non keratinized stratified squamous to simple columnar in the stomach (lots of glands)
What are the differences in SM motility in the orad vs. caudad area of the stomach?
Orad area relaxes during swallowing
Cudad area contracts to empty the stomach
What are rugae?
folds on the stomach epithelium that help with mechanical breakdown of food
Characteristics of gastric mucosa:
Epithelium
Made of?
- simple columnar epithelium
- reticular and collagen fibers, secretions release facilitated by muscularis mucosae
Characteristics of gastric submucosa:
type of CT?
contains?
-dense irregular CT
collagen, elastic fibers, vessels, lymphatics, meissner’s plexus
Characteristics of gastric muscularis externa
Features?
-3 muscle layers (oblique, circular and longitudinal), circular thickens and forms the pyloric region
Characteristics of the gastric serosa:
type of CT?
Contains?
- loose CT
- blood vessels
What are fundic (gastric) glands?
What are the parts of the gastric glands?
branched glands at the muscularis mucosae layer of the gastric mucosa
gastric pit (surface), isthmus (narrow region in between), gastric gland
What are surface mucous cells and mucous neck cells?
- line the lumen and gastric pits of the gland
- cells with round nuclei and apical granules found in the neck of the gland
