Histo of Esophagus and Stomach Flashcards
Main 4 layers of the GI tract tissue from lumen to superficial?
Mucosa
Submucosa
Muscularis externa
Adventitia or Serosa
Which main layer of the GI tract tissue varies the most over the course of the organs?
Mucosa
Mucosa has 3 layers, from lumen to more superficial?
Lining epithelium - VARIES
Lamina propria
Muscularis mucosae
In the lamina propria layer of the Mucosa, what will you find?
Loose CT that is well vascularized and contains lymphatic nodules and WBCs
Does the muscularis mucosae layer of the Mucosa control food movement?
NO - controls mobility and infoldings of mucosa
Describe the Submucosal layer in the GI tract
Dense irregular CT with neurovasculature and lymphatics and sometimes glands
In what regions of the GI tract does the Submucosal layer have glands?
Esophagus and the Duodenum
How many layers does the Muscularis Externa have?
2
What are the layers of the Muscularis Externa?
Inner circular layer
Outer longitudinal layer
Function of the inner circular layer of the Muscularis Externa?
Constrict lumen
Function of the outer longitudinal layer of the Muscularis Externa?
Shorten tube
What resides between the inner circular layer and the outer longitudinal layer of the Muscularis Externa?
Neurovascular plexuses
Mesothelium
Simple squamous epithelium
When the Adventitia is covered with Mesothelium
Serosa
Areas without Mesothelium
Adventitia
Areas without mesothelium… are they intraperitoneal or retroperitoneal?
Retroperitonal (adventitia)
What are the main mucosal types along the GI tract?
Non-keratinized stratified squamous OR
Simple Columnar epithelium
Where will you find Non-keratinized stratified squamous and what is its job?
Oral cavity, pharynx, anal canal
Job = PROTECTION
Where will you find Simple columnar epithelium?
Stomach
Small intestines
Large intestines
In the stomach, describe the mucosa there
Simple columnar epithelium packed with glands
Job = SECRETION
In the small intestines, describe the mucosa there
Simple columnar epithelium arranged as villi with crypts, may or may not have glands
Job = ABSORPTION
In the large intestines, describe the mucosa there
Simple columnar epithelium packed with glands and goblet cells
Job = ABSORPTION AND PROTECTION
What are the 2 plexuses that innervate the GI tract?
Submucosal plexus of Meissner
Myenteric plexus of Auerbach
Which plexus is in between the inner circular layer and the outer longitudinal layer of the Muscularis Externa?
Myenteric plexus of Auerbach
What does the neurovascular plexuses control?
Peristaltic contractions (move food) down muscularis externa AND Secretory activities of the mucosal and submucosal glands
Preganglionic axons of the parasymp. ___ motility
INCREASE
Postganglionic axons of the symp. _____ motility
DECREASE
What type of epithelium does the Mucosal layer of the esophagus contain?
Nonkeratinized stratified squamous
The submucosal layer of the esophagus contains what?
Collagen, elastic fibers, blood vessels and venous plexuses
Increased pressure can cause dilation of submucosal venous sinuses in the esophagus
Esophageal varices
What type of glands may be seen in the esophagus?
Cardiac esophageal glands in lamina propria and submucosal glands
Describe the muscularis externa layers in the upper third of the esophagus?
Skeletal muscle
Describe the muscularis externa layers in the middle third of the esophagus?
Smooth and skeletal muscle
Describe the muscularis externa layers in the lower third of the esophagus?
Smooth muscle
GERD
Reflux of gastric contents, causes chronic inflammation and difficulty swallowing
If GERD is chronic, what can occur?
Nonkeratinized stratified squamous will transition to columnar mucus-secreting/glandular = Barrett’s esophagus
Place where the nonkeratinized stratified squamous transitions to simple columnar
Gastroesophageal junction - very sharp transition
Rugae
Longitudinal folds of gastric mucosa that expand during eating - covered with gastric pits
Gastric glands produce mucosal barrier for protection and reach lumen via?
Gastric pits on Rugae
What type of epithelium is present in the mucosal layer of the stomach?
Simple columnar
What type of glands does the lamina propria contain in the stomach?
Cardiac, gastric and pyloric
What facilitates release from gastric glands?
Muscularis Mucosae
What are the layers in the Muscularis Externa in the stomach?
Oblique
Circular
Longitudinal
What layer in the Muscularis Externa thickens to form the pyloric sphincter?
Circular
Does the stomach have adventitia or serosa?
Serosa!
What are the parts of a gastric gland?
Gastric pit
Neck/isthmus
Gastric gland
Where in the mucosal layer do the gastric glands begin?
Muscularis mucosae
What are the cell types found on the gastric glands?
Surface mucous cells
Mucous neck cells
Chief cells
Parietal cells
What do mucous cells of the gastric gland release?
Mucin to neutralize acid environment
Where are surface mucous cells found?
Line lumen and gastric pits
Where are mucous neck cells found?
In gastric gland neck
Where are chief cells found?
Inferior 1/3 part of gastric glands
How do chief cells stain in gastric glands?
Abundant granules, basal nuclei and basophilic cytoplasm
What do chief cells in gastric glands release?
Pepsinogen - converted to pepsin
Gastric lipase
= protein digestion
Where are parietal cells found?
Upper segment and neck of gastric glands
How do parietal cells stain in gastric glands?
Large cells, central round nuclei and cytoplasm stains eosinophilic
What do parietal cells in gastric glands produce?
HCL and intrinsic factor
Gastric ulcers
Erosive lesions in mucosa that extend deeper - painful
What are some causes of gastric ulcers?
Bacterial infection
NSAIDS
Overproduction of enzymes or underproduction of mucous/bicarbonate
Cells that are scattered in gastric mucosa that release hormones essential for digestive function
Enteroendocrine cells
