Histology of the GI Tract Flashcards
Define a Tissue
A group of cells that work together and perform the same function
Cell + Extracellular substance
An organ is 2 or more tissue types
How do we determine the type of epithelium from a histological slide?
Look at the cell shape in the surface layer.
Even if theres some others in the low layers
What are the layers of the gut tube?
Mucosa - Epithelium - Lamina Propria - Muscularis Mucosae Submucosa Muscularis Externa - Inner circular - Outer longitudinal
Compare to the layers of blood vessels layers
Blood Vessel:
- Tunica Intima
- Internal Elastic Lamina
- Tunica Media
- External Elastic Lamina
- Tunica Adventitia
Tunica Intima = a single layer of squamous epithelium on a basement membrane
Compare to resp. tract layers
- Resp. Mucosa
- Submucosal Layer
- C-Shaped Cartilage layer + Trachealis muscle
- Adventitia Layer
How do we differentiate glands between mucosa and submucosa?
Look for the muscularis Mucosae
Describe the epithelium of the oesophagus?
Stratified Squamous Non-keratinised epithelium
What is found in the submucosa of the oesophagus?
Mucous glands
How does the muscle of the oesophagus vary?
Upper 1/3 skeletal
Lower 1/3 is smooth
Middle 1/3 is both
How do we differentiate the stomach from other GI tract areas?
- 3rd inner oblique layer of muscularis externa
- Gastric pits leading to up to 7 tubular glands
- Mucosal glands
What cell types are present in a gastric gland?
Parietal - Stain pink like a poppy up the side of glands
Chief - Purple, collect around base of gland
How do we differentiate between sections of small intestine?
Duodenum - Submucosal glands (brunner’s)
Ileum - Loads of peyers patches
Jejunum - Neither
What/Where are Paneth cells?
Cells at the bottom of cryps of lieburkhun in intestine, (very bottom below stem cells)
The key effectors of innate mucosal defence they produce lots of antimicrobial peptides like alpha defensins and lysozymes.
How do we tell the large intestine histologically?
- Patches of Taenia Coli outside Muscularis Externa
- Thick mucosa
- No villi, but are crypts
- Crypts lined with goblet cells (remember mucous doesn’t stain so very visible close up)
How do we spot a gland?
Secretory acini:
- Roundish shape of columnar cells with nuclei at hte base and maybe with a space in the middle
Duct:
- Mainly epithelium & connective tissue surrounding a space
