Histology Of Upper GI Tract Flashcards
What is the function of the small intestine?
Digestion via conversion into soluble form for absorption
What are the 4 major organs of the digestive tube after the oral cavity?
Esophagus, stomach, small intestine, large intestine
Name the layers of each organ from lumen to outside
Mucosa, submucosa, muscularis externa, adventitia/serosa
What are the 3 components of the mucosa?
Epithelial lining with mucosal and submucosal glands and ducts
Lamina propria w/vascularized loose CT
Smooth m.
What parts of the digestive tract have stratified squamous epithelium?
Oral cavity, oropharynx, esophagus, anal canal
What parts of the digestive tract have simple columnar epithelium?
Stomach, small intestine, large intestine, rectum
What is the function of the epithelium (for all of the gi tract)?
Selective permeable barrier
Transport, digestion, absorption
Produce hormones
What is the lamina propria made of?
What is located there?
What does the lamina propria of the small and large intestines contain?
Vascularized loose CT
MPL - marcophages, plasma cells, lymphocytes
Peyer’s Patch or GALT
What is the purpose of the muscularis mucosae of the mucosal layer?
Increase contact area w/food
Propel and mix food in GI tract
What is the submucosa made of?
Where are glands present in the submucosa?
Dense irregular CT
Esophagus and duodenum
What is the function of the rugae, plicae, and villi?
Increase surface area for absorption
What are the 2 layers of muscularis externa?
Circular layer - inner layer around lumen
Longitudinal layer - outer layer along the tube
Contraction reduces the lumen and shortens the tube
Both smooth m.
Give the characteristics of the adventitia
Outside the peritoneal cavity
Binds to body wall
Loose CT
Blood vessels and Nerves ONLY
Give the characteristics of the serosa:
W/in the peritoneal cavity
Loose CT
Simple squamous epithelium
Blood vessels, nerves, AND FAT
What does the lower esophageal sphincter do?
Prevents reflux and regurgitation of stomach contents through contraction
Must relax for food to pass when swallowing
Where is the upper esophageal sphincter located?
Near the cricopharyngeus muscle
What kind of epithelium is the esophagus?
Non-kertanized stratified squamous
What kind of muscle is the upper 1/3 of the esophagus? Fx?
Lower 2/3 muscle? Fx?
Skeletal, voluntary swallowing
Smooth, peristalsis
Where does the mucosa transfer from stratified squamous to simple columnar?
At the gastroesophageal junction
What does the UES participate in?
Beginning of swallowing
what is Barrett’s esophagus?
Due to what?
What does it predispose you to?
Change in esophageal epithelium from stratified squamous to simple columnar
Due to GERD
Adenocarcinoma of the esophagus
What is the function of the stomach?
Homogenize and chemically process food
What makes up the orad area of the stomach?
Cardia and fundus, LES
What makes up the caudad area of the stomach?
Body and antrum
Regulates gastric emptying
What are cardiac glands like?
What are they lined by?
Simple tubular, coiled at lower end
Mucus-secreting cells
What are the 5 types of gastric glands?
Mucous neck Chief Parietal Stem Gastroenteroendocrine cells
What are the 2 classes of mucus producing cells?
Surface mucous cells lining the pit
Mucous neck cells located at the opening of the gastric gland into the pit
What do mucous cells produce?
What is formed?
What is trapped?
Mucins and glycoproteins
Insoluble gel that forms protective gastric mucosal barrier
Bicarbonate ions and neutralizes acidic pH
Where do chief cells predominate?
Where are they found?
What do they make and how?
Lower 1/3 of the gastric gland
Pyloric antrum NOT in cardiac glands
Pepsinogen and ultimately pepsin via exocytosis
What do parietal cells secrete?
HCl and intrinsic factor
What causes autoimmune gastritis?
What is the result?
Autoantibodies to H-K dependent ATPase and to intrinsic factor
Result is decreased HCl and lack of intrinsic factor leading to B12 deficiency thus producing pernicious anemia
What stimulates parietal cells to make HCl?
What produces these things?
ACh and Gastrin
Enteroendocrine cells
What does Helicobacter pylori do?
What is the result?
Survives and replicates in the gastric lumen, can live in the pyloric antrum
Acid peptic ulcers and adenocarcinoma of the stomach
Gastroenteroendocrine cells are members of what?
What are the 3 main functions of peptide hormones?
DNES
Regulation of water/electrolyte metabolism and enzyme secretion
Regulation of gi motility and mucosal growth
Stimulation of the release of other peptide hormones
What releases secretin? When?
Secretin effects?
What does secretin stimulate?
Cells in the duodenal glands of Leiberkuhn when gastric contents enter the duodenum
Stimulates Brunner’s glands bicarbonate to control gastric acid secretion and regulate pH of the duodenum
Also stimulates chief cells to secrete pepsinogen, inhibits Gastrin (no HCl is made)
What makes Gastrin?
Main function?
What else can Gastrin activate?
G cells in pyloric antrum
Stimulate HCl production via parietal cells
CCK to stimulate gallbladder contraction
What produces CCK?
Function?
Duodenum
Stimulate gallbladder, contracts/relaxes sphincter of Oddi when protein and fat-rich chyme enters duodenum
Where is GIP produced?
What does it stimulate?
Duodenum
Insulin release when glucose is in the small intestine
How is motilin released and from where?
What does it stimulate?
Cyclically every 90 minutes during fasting from upper small intestine, neurally controlled
Stimulates gi motility
Where is Ghrelin produced?
Where does it bind?
What does it stimulate?
Stomach (fundus)
GH-secreting cells of the anterior hypophysis
Stimulates secretion of growth hormone, inc. during fasting
What fibers predominate in the lamina propria?
What is rare?
Reticular and collagen fibers
Elastic fibers
At the level of the distal pyloric antrum, the circular muscle thickens to form what?
Annular pyloric sphincter
What increases surface area to facilitate digestion?
Villi
