Histology of the upper GI tract: Esophagus and stomach Flashcards Preview

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Flashcards in Histology of the upper GI tract: Esophagus and stomach Deck (27):

What is the outer layer of the esophagus called?

-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?



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


What doe GIP do?

stimulates insulin release when GLc is detected in the SI
-also made by the duodenum


What does Motilin do?

It is just released cyclically when fasting, neural control mechanism regulates it


What does Ghrelin do?

made in the fundus of the stomach
-binds receptors in Growth hormone-secreting cells
-stimulates secretion of growth hormone
-levels increase during fasting triggering hunger by acting on the hypothalamic feeding centers