Histology of the Esophagus & Stomach Flashcards
4 layers of the GI tract?
- ) Mucosa
- ) Submucosa
- ) muscularis externa
- ) serosa/adventitia
Which of the 4 layers differs along the GI tract?
The mucosa, mainly. The other layers do differ, albeit slightly.
What are the three components of the mucosal layer?
- ) Epithelial layer
- ) Lamina propria
- ) Muscularis mucosae
Describe the epithelial layer of the mucosa
It varies from segment to segment but is largely simple columnar
Describe the lamina propria of the mucosa
Vascularized loose CT with contained lymphatic nodules, lymphocytes, macrophages
What is the muscularis mucosae?
A thin layer of muscle that controls the mobility of the mucosa and mucosal glands.
It is NOT involved in peristalsis
What is the submucosal layer comprised of?
Dense irregular CT with neurovasculature and lymphatics. Glands might also be present
What two layers make up the muscularis externa?
Inner circular and outer longitudinal layers
Contraction of the circular layer does what?
Moves food bolus down towards intestines
Contraction of the longitudinal layer does what?
Regurgitation
What does serosa mean?
Covered by peritoneum and mesothelium
What does adventitia mean?
Retroperitoneal, without mesothelium covering
Parasympathetic innervation of the GI tract is via which nerves?
Vagus and pelvic. Long presynaptic, postsynaptic are intramural (within wall of an organ or cavity)
Sympathetic innervation of the GI tract is via which nerves?
Greater, lesser, least and lumbar splanchnics
What are the two enteric plexus’? What are their functions?
- ) Submucosal plexus of Meissner
- ) Myenteric plexus of Auerbach
Function in peristaltic contraction or muscularis external and movements of muscularis mucosae
Where is the submucosal plexus of Meissner located?
In the submucosa (or between submucosa and inner circular)
Where is the myenteric plexus of Auerbach located?
Between the inner circular and outer longitudinal layers
Is the esophagus made of serosa or adventitia?
Both!
The thoracic esophagus = adventitia
The diaphragmatic esophagus = serosa
Where do the cardiac esophageal glands reside?
In the lamina propria of the terminal esophagus
The mucosa of the esophagus is made of what cell type?
Nonkeratinized stratified squamous
The submucosa of the esophagus has what which makes them unique?
A submucosal venous plexus which drains into the systemic and portal venous system.
Increase in pressure in the submucosa can cause what?
Esophageal varices due to dilation of the submucosal venous sinuses
The muscularis of the esophagus changes depending on what part of the esophagus you are in. What kind of muscle is in the upper, middle, and lower third?
Upper = skeletal Middle = skeletal and smooth Lower = smooth
What is the epithelium of the stomach like?
Simple columnar and glandular, with pits and glands.
