Histology of Esophagus, Stomach, SI, LI Flashcards
What are the layers from lumen to superficial of the GI tract?
mucosa
submucosa
muscularis externa
serosa/adventitia
What does the mucosal layer consist of?
- lining epithelium
- lamina propria
- muscularis mucosae
What is in the lamina propria?
lymphatic nodules, lymphocytes, plasma cells, macrophagaes
What is the fxn of the muscularis mucosae?
controls mobility of mucosa and glands
What is in the submucosal layer?
- dense irregular CT
- glands present in esophagus and duodenum
What is the difference between adventitia and serosa?
Serosa: adventitia covered by mesothelium and suspended by mesentery/peritoneal fold
Adventitia: without mesothelial covering
What kind of epithelium is protective?
nonkeratinized stratified sqamous
Where would you find nonkeratinized stratified squamous epithelium?
oral cavity
pharynx
anal canal
What epithelium is secretory?
simple coumnar packed with glands
Where would you find simple columnar epithelium?
stomach
What epithelium is absorptive?
simple columnar with villi that contain crypts
–>glands in SI
What type of epithelium is absorptive and protective?
simple columnar arranged in closely packed glands with extensive goblet cells
Where is protective/absorptive epithelium found?
LI
Where is absorptive epithelium found?
SI
Does the esophagus have serosa or adventitia?
Both
thoracic= adventitia
inferior to diaphragm= serosa
Where are cardiac esophageal glands?
lamina propria of terminal esophagus
What cell types make up submucosal glands in the esophagus?
mucous and serous drained by single duct
Increased pressure in submucosal venous plexus of esophagus can cause __________-
esophageal varices
What type of muscle is the upper third esophagus?
skeletal
What type of muscle is middle third esophagus?
skeletal and smooth
What type of muscle is lower third esophagus?
smooth
Describe Barrett’s esophagus/metaplasia
d/t chronic GERD:
nonkeratinized stratified squamous becomes columnar mucus-secreting epithelium in TRANSITION ZONE
How to identify stomach from esophagus
Transition from nonker strat sqamous to simple columnar with lots of glands and pits
What protects the mucosal surface of the stomach?
gastric mucosal barrier
What is stomach rugae (mucosal folds) sovered by?
gastric pits
Does the stomach have adventitia or serosa?
serosa
What cells make up the gastric glands?
surface mucous mucous neck parietal (IF, HCl) chief (pepsinogen, lipase) G cell (gastrin)
What cell is in the inferior regions of gastric glands, has abundant RER and secretory granules?
chief cells
What cells is near neck of gastric gland, large, one or two central nuclei and intensely eosinophilic (pink)?
parietal cell
What is the difference between cardiac and pyloric glands in histo?
cardiac are tubular and coiled–>appear circular in oblique sections
pyloric are mainly branched
Where are plicae circulares visible?
jejunum, not really in ileum
What are villi covered with?
simple columbar with enterocytes and goblet cells
Where are lacteals?
lymph in the middle of villi in SI
What are intestinal glands lined with ?
simple columnar epithelium
What cells are in intestinal gland epithelium?
Enteroendocrine
Paneth
M (microfold)
Intestinal stem cells
What cell secretes gastrin, secretin, GIP, motilin and CCK to help control gut motility?
enteroendocrine cell
What is a pyramidal-shaped cell at the base of intestinal glands?
paneth cell
What is the function of paneth cells?
innate immunity, secretes antimicrobial substances to regulate normal bacterial flora
What reside in a niche at the crypt base, near Paneth cells?
intestinal stem cells
–>diff into goblet, enterocyte, and enteroendocrine cells
What are locaed in ilea mucosa overlying peyer patches?
M cells
–>transport particles and microorganisms (gram -)
What is the fxn of M cells?
internalize gram - bacteria and transfer to immune cells
–>fxn as Antigen-transporting cells
How do you differentiate duodenum from pylorus?
abundant Brunner’s glands in submucosa, deep to muscularis mucosae, lots of deep villi
What are the fxn of Brunner;s glands in submucosa of duodenum?
neutralize acidic chyme
Are there submucosal glands in jejunum?
NO
Where are long finger-like villi with lacteals located?
jejunum
Where are peyer’s patches located?
ileum
–>circles under short villi (c/t jejunum)
Hallmarks of LI
- simple columnar epithelium with intestinal glands
- goblet cells
- NO intestinal villi
Does the SI and LI have adventitia or serosa?
Serosa
Describe anal transitional zone (AZT)
simple columnar epithelium–>stratified squamous epithelium
middle 1/3
