Lecture 17 and 18 Gastrointestinal Flashcards
What is this and how many layers
Mucosa in the esophagus
Epithelium (E): protects, secretes via glands, absorbs
Lamina propria (LP): CT for support and defense GALT lymphoid
Muscularis mucosa (MM): smooth muscle
What is this layer?
Submucosa
Esophagus & duodenum have specific mucus-secreting submucosal glands
What is the arrow?
Submucosal Plexus
In the MUCOSA section
What layer is this? and its two layers?
Muscularis externa
inner circular (IC) &
outer longitudinal (OL)
FXN: peristalsis
What is the Dotted area? in the muscular external
Myenteric plexus – autonomic ganglia part of enteric nervous system
Housed between IC & OC
Innervates muscularis externa
What digestive tube is this?
esophagus - Transport of food
Mucosa
Non-keratinized stratified squamous epithelium
(E) – protection from abrasion as food is transported to stomach
Muscularis mucosa – visual aid to distinguish esophagus from anal canal
What is this?
** Submucosa**
Esophageal glands (EG) – secrete mucus for lubrication
Ducts (D) with stratified cuboidal epi transport mucus to lumen
What is this?
Gastroesophageal junction
Sharp transition from stratified squamous to simple columnar epithlieum
What clinical correlation is associated with Gastroesophageal junction
GERD
astroesophageal reflux disease (GERD) is caused by reflux of stomach acids into esophagus. Inflammation of esophageal mucosa leads to metaplasia: stratified squamous to simple columnar epithelium with mucus-secreting goblet cells.
Due to sharp change
Where is this and what is the arrow?
stomach: gastric glands
Blue= Gastric Pit
- Surface Mucous cells are simple columnar
- Parietal cell – secretes HCl to activate pepsinogen
- Chief cell – secretes pepsinogen (pale-staining apical granules)
- Enteroendocrine cells- poor staining
What is this?
Surface mucous cell – protects mucosa by secreting alkaline mucus
Lines gastric pits
Apical mucous granules – pale with H&E, PAS positive
What two cell types are these.
Parietal cell – secretes HCl to activate pepsinogen
Large cell with pink cytoplasm… EGG LIKE
Chief cell – secretes pepsinogen (pale-staining apical granules)
Lots of basal rER (purple)
What are 1 and 2
Parietal cells
Chief cells
What cell is the yellow?
Enteroendocrine cell – small, clear staining cytoplasm (H&E)
Can notice the parietal cells and chief cell
What cell is this?
Hint only can see TEM
G cells secrete gastrin – increases activity of parietal & chief cells
stomach Regulator
Chief cell
What is this?
Rugae
A ruga consists of a fold of submucosa (SM) that is covered by gastric mucosa (M)
Easily confused with circular folds in small intestine
Rugae are covered with gastric mucosa – dense appearance with narrow gastric pits
Notice in the IC and OL and which on is apart of this structure
Pyloric sphincter (PS) is an anatomical sphincter
An anatomical sphincter forms from permanent thickening of IC layer of muscularis externa
Relaxation of sphincter allows gastric emptying
Inner circular layer is the pyloric sphincter
Small intestine has widely spaced projections – villi
Blue vs white box
Blue - Folded up into widely- spaced villus (plural = villi)
White= - Folded down into narrow short intestinal gland Narrow lumen compared to villi
Folds increase surface area for absorption & secretion
4 cell types of epithelium in Small I
Enterocyte (E)
Goblet cell (G)
Paneth cell
M cell
what are these?
Enterocytes absorb digested proteins, carbs, fats
Enterocytes also secrete some enzymes to digest carbs & activate enzymes from pancreas
What are these yellow arrows
Goblet cell – shaped like a wine goblet
What is this?
goblet cell
Mucus secretion protects epithelium
from self-digestion
What cell types are these
Hint only found in one area of GI
Paneth cells have apical acidophilic granules
Small Intestine
What cells cell types are these
enteroendocrine cell
I cell
secretes cholecystokinin (CCK)
Empty bile from gallbladder Secretion of pancreatic enzymes
S cell
S cell – secretes secretin Secretion of watery alkaline fluid by pancreas
What cell type is this?
M cell
No microvilli – not absorptive like enterocytes
Relay luminal antigens to lymphocytes below
What are these
Peyer’s patch - in ileum only, GALT forms cluster of nodules (often on one side of GI tube)
What and where is this?
Small intestine has Brunner’s Glands
Secretes alkaline mucus – raises pH of partly digested food (chyme) from stomach
What is this?
Circular folds (plicae circulares)
submucosa (SM) folds up into lumen &
covered by mucosa (M)
Circular folds don’t flatten – permanently increases surface area for absorption
rugae are covered with villi
A. Villis
B. Circulus fold
c. Short intestinal gland
What part of GI tract is this?
large intestine
Recall parts of large intestine: cecum, appendix, colon, & rectum
Simple columnar epithelium
NO villi
Large Intestine.
Notice the difference between SmI
Enterocyte (E) – reabsorb water; dehydrate feces
Goblet cell (G) – lubrication; abundance gives mucosa bubbly appearance
SMI only one cell type
Lamina propria contains lymphocytes & lymphoid nodules
GALT
What are these
Teniae coli
Outer longitudinal layer (OL) of muscularis externa (ME) is reduced to a set of three longitudinal bands – teniae coli (TC)
Teniae coli are modified outer longitudinal layer
What is this
Liver
Each lobule consists of alternating rows of liver cells (H: hepatocytes) and…
A
Large no microvilli
