Alimentary System I - Esophagus and Stomach Flashcards
Name the four layers of GI walls.
- Mucosa
- Submucosa
- Muscularis externa
- Adventitia/serosa
Describe the composition of the mucosa layer.
3 layers
- Epithelium
- Loose CT called the lamina propria
- Smooth muscle layer called the muscularis mucosae
What type of tissue makes up the submucosa?
Loose or dense CT
What type of muscle is usually found in the muscularis externa of the esophagus? How is the muscle organized? What is the one exception?
Smooth muscle except in the upper third of the esophagus which is skeletal muscle, and the middle third is a mix of skeletal/smooth muscle. Organized into orthogonal layers for peristalsis.
Where does serosa occur?
Where the organ is covered with mesothelium.
What two organs does the esophagus connect?
The oropharynx to the stomach.
What is responsible for preventing acid reflux?
The esophogeal sphincter.
What cell type is found in the epithelium of the esophagus?
SSNKE.
Name the layers of the esophagus.
Epithelium, lamina propria, muscularis mucosa, submucosa, muscularis externa (with serosa connected to mesothelium where the esophagus enters the stomach).
What glands are unique to the submucosa of the esophagus? What epithelial cell type is found here?
Submucosal esophogeal glands, which secrete lubricant to protect the mucosa from food passing through. Stratified cuboidal epithelium.
What proteins do the secretions of the submucosal esophogeal glands contain?
Lysozyme and epidermal growth factor (EGF)
What epithelial cell type is found in the stomach?
Simple columnar.
What is the area called where the epithelial cells of the esophagus transition to the columnar cells of the stomach?
The squamocolumnar junction.
Name the three stomach regions.
Cardia, fundus/body, pyloris.
Describe the gastric glands of the cardia.
Short pits, short glands.
Describe the gastric glands of the fundus/body.
Short pits, long glands.
Describe the gastric glands of the pyloris.
Long pits, short glands.
What is the primary function of the muscularis externa layers of the fundus/body?
Churning food.
What does gastrin do? What secretes it?
It stimulates digestion by increasing gastric motility and secretion of HCl. It is secreted by enteroendocrine glands found in all three stomach regions.
What cells are found on the surface throughout the stomach? What is their function?
Surface mucous cells. Function is to secrete protective mucous.
How do surface mucous cells secrete mucus?
They store mucin granules in their apical regions and release them through exocytosis once stimulated.
How do surface mucous cells stain?
Poorly with H&E but well with PAS.
Name three cells that are found in fundic region glands.
- Mucous cells
- Parietal cells
- Chief cells
What are the two major functions of parietal cells?
- Produce HCl
2. Produce intrinsic factor
Are parietal cells eosinophilic or basophilic? Why?
Eosinophilic because they have abundant mitochondria for proton pumps.
By which system do parietal cells increase their surface area for greater H+ secretion?
Complex tubulovascular system.
What is an intracellular canaliculus?
The system by which parietal cells increase surface area for greater acid production after a meal.
Where are chief cells found and what do they do?
Found deep within gastric glands of the fundic region. They produce pepsinogen.
How do chief cells stain? Why?
Basophilic due to abundant ribosomes.
Where are mucous neck cells found and what do they do? How are they best visualized?
Found in the neck of gastric glands, they protect glands from the acid pH and active pepsin. Must be stained with mucin stains, PAS.
Intrinsic factor is important for absorption on which vitamin? Deficiency of this vitamin can lead to what disease?
B12. Deficiency can lead to Pernicious anemia.
What is the esophogeal hiatus?
Where the esophagus enters the abdominal cavity.
Compare Miessner’s plexus and the Auerbach’s plexus of the esophagus.
Miessner’s is located in the submucosa, and Auerbach’s is located just outside the circular muscle layer in the muscularis externa.
Is the esophagus covered with serosa?
Just for a short bit before it enters the stomach. The rest is adventitia!!
