Histology: GI Tract Flashcards
What are the 4 histologic layers of the GI tract?
Mucosa; submucosa; muscularis externa, and adventitia/serosa
What are the components of the submucosal layer?
- Connective Tissue
- Vessels
- Meissner Plexus
What is the location of the Meissner Plexus?
Submucosa
What is the location of the Auerbach Plexus?
In between the inner and outer muscle layers in the muscularis externa
What epithelium covers the esophagus?
Nonkeratinized stratified squamous epithelium
What epithelium covers the stomach?
Columnar epithelium
What epithelium covers the small intestine?
Villi and microvilli
What epithelium covers the appendix?
Columnar epithelium
What epithelium covers the large intestine?
Columnar epithelium with no paneth cells but a lot of goblet cells
What epithelium covers the anal canal?
Stratified Squamous Epithelium
What are the 4 parts of the stomach?
- Cardia
- Fundus
- Body
- Pylorus
What do parietal cells secrete?
HCl and Intrinsic Factor
What do chief cells secrete?
Pepsinogen
Crypts of Lieberkuhn
The epithelia of the villi extend down into the lamina propria where they form crypts. Many important cells reside in the crypts, including those involed in host defense and signaling.
Taenia Coli
Three narrow bands of longitudinal muscle
Contrast vili vs plicae circulares.
Plicae circulars are are large valvular flaps projecting into the lumen of the small intestine that are covered with villi.
What cells make up the epithelium of the inside of the mouth and surface of the tongue?
Nonkeratinized stratified squamous epithelium
What is beneath the submucosa?
Muscularis externa
When is the outermost layer of tissue called serosa?
Call serosa if covered my mesothelium; adventitia otherwise
What is unique about the muscularis externa in the esophagus?
It has some skeletal muscle fibers
Cardia
1st part that is separated from the esophagus by the cardiac sphincter
Fundus and Body
Largest part of the stomach and the glands have parietal and chief cells
Pylorus
Glands are mainly mucus secreting with there being 2 specialized cells: G cells and D cells
What do D cells secrete?
Somatostatin
What do G cells secrete?
Gastrin
What color are the parietal cells?
Pink
What color are the chief cells?
Blue
What is the feature of the duodenum?
Brunner Glands
What is the feature of the jejunum?
Long villi and increased goblet cells – no Brunner glands or Peyer patches
What is the feature of the ileum?
Short villi, many goblet cells, and lymphatic nodules in the submucosa called Peyer patches
