Histology of Esophagus & Stomach Flashcards
What are the four layers (lumen to superficial) of the GI tract?
- mucosa
- submucosa
- muscularis externa
- serosa (intraperitoneal) or adventitia (retroperitoneal)
From region to region, throughout the GI tract, which layer differs the most?
mucosa
What are the three components (lumen to superficial) of the mucosa layer?
- lining epithelium
- lamina propria
- -vascularized loose CT; contains lymphatic nodules
- muscularis mucosae
- -thin layer of muscle that controls mucus glands
What are characteristics of the submucosa layer of the GI tract?
- dense irregular CT
- neurovasculature and lymphatics
- glands may be present (esophagus and duodenum)
- contains submucosal plexus of Meissner
What are characteristics of the muscularis externa?
- two layers of muscle: inner circular and outer longitudinal
- myenteric plexus of Auerbach located b/w the two muscle layers
What are the characteristics of the serosa or adventitia?
- serosa: on intraperitoneal organs; mesothelium
- adventitia: on retroperitoneal organs; no mesothelium
What are the characteristics of the mucosa of the esophagus?
- nonkeratinized stratified squamous
- numerous folds (into the submucosa)
- muscularis mucosae only present in lower segment
What are the characteristics of the submucosa in the esophagus?
- collagen and elastin fibers
- contain many small blood vessels
-has a venous plexus that drains to both systemic and portal systems
What are the characteristics of the muscularis externa in the esophagus?
upper third = skeletal muscle
middle third = skeletal and smooth muscle
lower third = smooth muscle
Does the esophagus have serosa or adventitia?
BOTH!
thoracic esophagus = adventitia
abdominal esophagus = serosa
What are characteristics of the mucosa layer of the stomach?
- simple columnar epithelium
- lamina propria contains glands
- reticular and collagen fibers predominate
What are characteristics of the submucosa of the stomach?
- collagen and elastin fibers
- arterioles, venous plexus, lymphatics present
- submucosal nerve plexus of Meissner
What are characteristics of the muscularis externa of the stomach?
- three layers
- -oblique, circular, and longitudinal
-circular muscle thickens in the pyloric region to form the pyloric sphincter
Does the stomach have serosa or adventitia?
serosa
-loose CT w/ vasculature
What are the two parts of the enteric nervous system?
submucosal plexus
–gland secretion and local blood flow
myenteric plexus
–GI mvmts
What is the parasympathetic control to the esophagus?
CN X
What is the sympathetic control to the esophagus?
cervical and thoracic spinal nerves
-postsynaptic fibers feed into the esophageal plexus
What is the parasympathetic control to the stomach?
CN X
What is the sympathetic control to the stomach?
thoracic spinal nerves (T6-T9)
- form greater splanchnic N.
- feeds into the celiac plexus
Clinical Correlation: Gastroesophageal Reflux Disease (GERD)
-causes chronic inflammation, ulceration, and difficulty swallowing d/t reflux of gastric contents
Clinical Correlation: Barrett’s Esophagus
-if GERD is chronic, the epithelium of the esophagus (near gastroesophageal junction) changes from nonkeratinized stratified squamous to simple columnar (more like stomach) d/t constant exposure to gastric juice
What are the four parts of the stomach?
cardia
fundus
body
pyloric antrum
What are the characteristics of the cardia of the stomach?
- 2-3 cm near the esophageal opening
- primarily involved in mucus production
What are the characteristics of the fundus of the stomach?
- projects to the left of the cardia
- site of gastric glands releasing acidic gastric juice
