4 Histo of the Stomach and Esophagus Flashcards
What are the layers of the GI tract from the lumen outward
Mucosa —> submucosa —> muscularis/muscalris externa —> serosa/adventitia
What are the layers of the mucosa
Lining epithelium, lamina propria, muscularis mucosae
What is found in the lamina propria
It is loose, vascularized CT
Lymphatic nodules, lymphocytes, plasma cells, and macrophages
What does the muscularis mucosae do
Controls mobility of mucosa as well as squeezes gland contents out
What kind of CT is found in the submucosal layer
Dense, irregular CT and glands in esophagus and duodenum
What are the layers of the muscularis/muscularis externa? What do they do?
Inner circular layer - constricts the lumen
Outer longitudinal layer - shortens the tube
What is between the layers of the muscularis/muscularis externa
Neurovascular plexuses
What cell type is mesothelium
Simple squamous
What is the serosa/adventitia layer made of
Loose CT and mesothelium
What cell type is the mucosa epithelium in the GI
Simple columnar
What are the main parasympathetic GI innervations
Vagus until splenic flexure
Pelvic splanchnic after splenic flexure
What is the sympathetic innervation of the GI
Greater, lesser, least, and lumbar splanchnic nn
What is the innervation found in the submucosa of the GI called
Submucosal plexus of Meissner
What is the innervation between the muscularis layers called
Myenteric plexus of Auerbach
What in the esophagus determines whether it has serosa or adventitia?
The diaphragm
Above - adventitia and adipose
Below - serosa
Where do cardiac esophageal glands reside
In the lamina propria (mucosa)
What are the submucosal glands
Consists of small lobules with mucous and serous cell types and are drained by a single duct
What are the layers of esophagus
Mucosa, submucosa, muscularis, and adventitia or serosa (adventitia above diaphragm)
Where is muscularis mucosa present in the mucosa of the esophagus
In lower segment
Increase in pressure of what layer of esophagus causes varices?
Submucosa, this is where the venous plexuses are
What kind of muscle is found in the muscularis of the esophagus
Upper third = skeletal muscle
Middle third = blend
Lower third = smooth muscle
What cell types meet at the gastroesophageal junction
Stratified squamous —> simple columnar
What are the two sphincters of the esophagus
Upper - anatomical and involved in swallowing reflex
Lower - functional and prevents reflux of gastric contents
What does GERD stand for? What does it cause?
GastroEsophageal Reflux Disease
Chronic inflammation, ulceration, and dysphagia
What can GERD cause in the long term?
Barrett’s esophagus
Esophagus epithelium replaced by stomach epithelium
What are people with Barrett’s esophagus at high risk for
Stomach cancer
What are the regions of the stomach
Cardia - 2-3 cm near esophageal opening
Fundus - projects to the left of cardia
Body - extensive central region
Pyloric antrum - ends at gastroduodenal orifice
What are the two stomach regions based on motility
Orad - fundus and upper body that relaxes during swallowing
Caudad - lower body and antrum, participates in regulation of gastric emptying
What are gastric mucosal folds called
Rugae
What protects the epithelium of the stomach
Mucosal barrier
What kind of cells are found on the stomach mucosa
Secretory simple columnar
What glands are found in the stomach mucosa
Cardiac, gastric and pyloric
What type of CT is found in the submucosa of the stomach? What other portion has this
Dense, irregular CT
GI
What are the muscle layers in the muscularis of the stomach
Oblique, circular, and longitudinal
What muscularis layer forms the pyloric sphincter
Circular
What do cardiac glands look like
They are single tubes that have coiled ends
What do cardiac glands secrete
Mucus
Where are the cardiac cells
They extend only a few cm from the gastroesophageal junction
What are the regions of the stomach’s glands
Pit (foveolar), neck, and body
What cells are found in the pit of glands
Mucous cells
What cells are found in the neck of glands
Mucous neck cells, stem cells, and parietal cells
What cells are contained in the upper body of glands? Lower?
More parietal cells, chief cells, stem cells
Parietal cells, more chief cells, more enteroendocrine cells
What is Ménétriers disease
TGF-α induced hyperplasia of surface mucous cells
What are the symptoms of Ménétriers disease
Nausea, vomitting, epigastric pain, gastrointestinal bleeding, diarrhea
What do parietal cells produce
Hydrochloric acid and intrinsic factor (glycoprotein that binds to B12)
What features of parietal cells allow them to function
Abundant mitochondria - for ATP production for ATPase pumps
Secretory/intracellular canaliculus - for vesicle production
Abundant H/K dependent ATPase
Where are chief cells primarily found
Lower 1/3 of gastric gland
Where are chief cells not found
Cardiac glands and pyloric antrum
What do chief cells contain and secrete
Zymogen granules of pepsinogen
What converts pepsinogen to pepsin
Acids
What stimulates pepsinogen release
Feeding
What do enteroendocrine cells of the stomach
Somatostatin, gastrin, ghrelin
What does gastrin do
Produced by G cells in pyloric antrum and stimulates production of HCl by parietal cells
What does somatostatin do
Produced by D cells and inhibits gastrin action
What does ghrelin do
Produced in gastric fundus
Binds to receptor in pituitary and stimulates GH
Increases with fasting and triggers hunger
How are pyloric glands diffrent than gastric pits
Pits are deeper and extend halfway through mucosa
Glands have larger lumen and are highly branched
What do pyloric glands produce
Mucus and lysozyme (lyses bacteria)
What cells are found in a high number in pyloric glands
Enteroendocrine cells and G cells (gastrin)
GALT in lamina propria
What is the difference between serosa and adventitia
Serosa is covered by peritoneum and adventitia is retroperitoneal
