Flashcards in GI Tract Deck (42)
What are the 4 layers of the GI tract?
Mucosa, Submucosa, Muscularis Externa, Serosa or Adventitia
What is the function of the Mucosa
What is the function of the Submucosa?
In the duodenum and esophagus, it has glands
In its the periphery, the Meyenteric plexus is found
What is the purpose of the Muscularis externa?
To mix and propel intestinal contents
What does the mucosa consist of? the functions?
Lamina propria (loose connective tissue that contains blood and lymphatic vessels+tissues, connective tissue cells, and wandering cells in connective tissues such as plasma cells and eosinophils),
Muscularis mucosae (smooth muscle that produces movement of mucosa creating ridges and valleys that facilitate absorption and secretion)
What kind of tissue is submucosa made of ?
Dense, irregular, connective- containing blood and lymphatic vessels and nerve plexus
Serosa vs. Adventitia. Who wins when?
Serosa when a simple squamous epithelium is present (the mesothelium)
Adventitatia when the part of the digestive tract is fixed directly to the abdominal or pelvic wall.
What are the four types of taste buds and their abundance in man? What cell types are they?
Filiform (none), Fungiform (few), Circumvallate (many), Foliate (many but not seen much in man)
All are stratified squamous except only Filiform is stratified squamous keratinized epithelium. (Taste buds have About 50-100 cells)
Where can tongue murcosal and serous galnds and adipose tissue be found?
in between skeletal muscle bundles
Where can esophageus glands proper be found? with what?
Submucosa of the esophagus along with connective tissues
Where are the esopogeal cardiac glands? What is the distance between them?
at either ends of the esophagus, 10 inches (25cm)
where is the esophageal adventitia and serosa?
above and below the diaphragm respectively.
What are the three major types of gastric mucosal glands?
Gastric or Fundic
What is the name for permanent invaginations into the lamina propria that serve as ducts for mucosal glands?
Order in pit length increasing
cardiac, gastric, pyloric
Of the gastric, pyloric, and cardia glands, which coil and which are straight?
Coiled: Cardiac and Pyloric
Describe the distribution of cell types according to glands of the stomach.
Pyloric glands: mostly mucous cells, few parietal cells, and few entereoendocrine cells that are hard to see
Gastric glands: mucous neck cells , parietal cells, chief cells, and enteroendocrine cells
Cardiac glands: Lysozyme and HCL producing cells
Is there a serosa in the stomach?
What kind of mucus is secreted from mucous neck cells? surface mucous cells?
soluble; biarcabonate rich, alkaline mucus that is insoluble, cloudy, or visible
Describe the structure of the Parietal cell and location
- It has an intracellular canniculus for secretion of HCL
- They can be binucleate
- It is located in the middle and upper part of the gastric gland
Describe the chief cell structure and location
- serous cells
- columnar shape
-located in the basal half of gastric glands
Describe the enteroendocrine cell location
base of gastric glands and individually dispersed
what hormones are secreted by enteroendocrine cells?
Where are gastric stem cells found?
isthmus and neck of mucosal glands
What cells are replaced by downward movement of stem cells? upward movement?
glandular cells; surface mucous cells
What 3 structural modifications facilitate absorption in the GI ?
Increased lumenal surface area by
1- Plicae circularis (valves of Kerckring)- permanent transverse circular folds of mucosa and submucosa (2-3x)
2. Villi: finger-like or leaf like projections of surface epithelium and lamina propria (10x)
3. Microvilli: projections of the plasma membrane (20x)
How is duodenum mucosa protected from gastric acid?
Brunner's glands secrete alkaline mucous that protects the duodenum from stomach acid
This also provide optimum pH for pancreatic enzyme secretion.
Where are Brunner's glands found?
in the submucosa of the duodenum
What are M Cells? It localizes what section of the GI tract?
M cells aka Microfold cells care a specialized epithelial that cover over Peyer's patch and delivers lympohcytes that it takes ulp to cells in Peyer's Patches (lymphatic nodules)
Peyer's patch are only found in the ileum thus M cells are a marker for the ileum.
It's basement membrane beneath is discontinous.