Histology of the upper GI tract: Esophagus and stomach Flashcards
What is the outer layer of the esophagus called?
adventitia
-it’s serosa for the rest of the GI tract
What is lamina propria?
vascularized loose CT under the epithelial layer
-lymphatic nodules and scattered immunocompitent cells
In what layer are glands present in the esophagus and the duodenum?
the submucosa
What are rugae (stomach) or Plicae (small intestine)?
folds that include both mucosa and submucosa
What extends alone into the lumen as villi?
mucosa
What does contraction of the circular muscle layer do?
reduces the lumen
What does contraction of the longitudinal muscle layer do?
shortens the tube
What is the difference between adventitia and serosa?
- adventitia is outside the peritoneal cavity while the serosa is IN the peritoneal cavity
- serosa seems to have more stuff in it
What does the lower esophageal sphincter do?
helps prevent reflux through contraction
-must relax to let the food through
What is the muscle like going down the esophagus?
goes from skeletal to smooth
What is the main difference between the esophagus and the stomach epithelium
Esoph has stratified squamous
-stomach has simple columnar
What is Barret’s esohpagus?
when abnormal columnar epithelium replaces the stratified squamous in the esophagus
-result of chronic GERD and predisposed to adenocarcinoma
What kinds of cells are in the gastric glands?
mucous neck cells chief cells parietal cells stem cells gastroenteroendocrine cells
What do mucous cells do?
2 classes
- both produce mucins which are glycoproteins
- make the protective mucus blanket which traps bicarb
What do chief cells do?
rapidly exocytose the pepsinogen in response to feeding
-not present in cardiac glands or pyloric antrum
What do parietal cells do?
make HCl and intrinsic factor
-they also have CA and the H+/K+ ATPase on the microvilli
What causes autoimmune gastritis?
autoantibodies to the ATPase and intrinsic factor
-results in lower acid in gastric juice and lower intrinsic factor
What is a secondary effect of autoimmune gastritis?
B12 deficiency which disrupts the formation of RBC’s int he bone marrow, leading to pernicious anemia
What stimulates parietal cells to secret HCl?
Parasympathetic Ach and the peptide gastrin made by the enteroendocrine cells of the pyloric antrum
*Ach also stimulates the release of gastrin
What was the bacteria that can live in the hostlie environment of the stomach?
Helicobacter pylori
-no clinical symptoms… can lead to peptic ulcers and adenocarcinoma
What are the functions of the gastroenteroendocrine cells?
- to make gastrin
- regulate water and electrolyte metabolism and enzyme secretion
- regulate GI motility and mucosal growth
- stimulation of the release of other peptide hormones
What is secretin?
- released by cells in the duodenal glands of lieberkuhn
- stimulates pancreatic and duodenal bicarb and fluid release to control the gastric acid secretion and regulates the pH of the exocrine pancreas
- also stimulates chief cells to secrete pepsinogen and inhibits gastrin release to reduce HCl secretion in the stomach
What does gastrin do?
stimulates production of HCl by parietal cells
-Gastrin is made by G cells in pyloric antrum
What does CCK do?
produced by duodenum
-stimulate gall bladder contraction and relaxation of the sphincter of Oddi when protein and fat-rich chyme enters the duodenum
