Lecture 1 Flashcards
- Histology of the GIT
What is the purpose of salivary glands?
- produce saliva
- secretes saliva into the oral cavity
What are salivary glands covered by and divided into? What is it made of?
- capsule and lobules
- connective tissue
How many salivary glands are there? What are they?
- 3
- Parotid, Sublingual, Submandibular
What type of cell lies deep to the basement membrane but superficial to the epithelium cells?
Myoepithelial cells
How many secreting units do acini have and what are they?
- 3
- Mucous, Serous, Mixed
What are the features of mucous acini cells?
- Oval shaped, large lumen
- Lined by columnar cells
- Flattened nucleus at basement membrane
- Contains large secretory granules of micinogen near the apex (in fresh condition- not present after staining)
What salivary gland contains majority of mucous acini?
Sublingual Gland
What are the features of serous acini cells?
- Spherical, smaller than mucous acinus
- Small lumen
- Lined by columnar/pyramidal cells
- Round nucleus at the basal part of the cell
- Alpha-amylase (digestive enzyme) secreted by acinar cells
What salivary gland contains majority serous acini?
Parotid Gland
What are the features of mixed acini?
- Spherical, smaller than mucous acinus
- Small lumen
- Lined by columnar/pyramidal cells
- Round nucleus at the basal part of the cell
- Alpha-amylase (digestive enzyme) secreted by acinar cells
What salivary gland contains mixed acini?
Submandibular Gland
How many surfaces does the tongue have and what are they?
- 2
- dorsal (top) and ventral (underside)
The tongue is covvered by a mucous membrane/ mucosa… how many layers does it have and what are they?
- 2
- Outer epithelium and inner lamina propria/corium
What type of epithelium is the tongue made up of?
- Stratified Squamous Non Keratinized epithelium
- Stratified Squamous Keratinized epithelium (over the papillae)
What is the lamina propria made of?
- connective tissue
- blood vessels
- serous and mucous glands
How many lingual papillae are there and what are they?
- 3
- Filiform, Fungiform, Circumvallate
What are the features of filiform papillae?
- ⅔ of the tongue
- No taste buds
- Small conical projections covered by horny keratinized cap
What are the features of fungiform papillae?
- Rounded top; narrow base
- Contains taste buds
- Present at the apex and along the lateral margins of anterior
- ⅔ of the dorsum of the tongue
What are the features of circumvallate papillae?
- 8 to 12 in number
- Largest papilla, situated in a depression
- Surrounded by the circular (vallate) sulcus
- Have rounded top and narrow base
- Contain taste buds on the their lateral wall
- The sulcus receives the opening ducts of serous glands (Von Ebner’s gland)
- Serous secretion of these glands distribute the substance to be tasted & wash out the debris in the sulcus
What are the four layers of the alimentary canal?
Mucosa, Submucosa, Muscularis externa, Adventitia (esophagus & duodenum)/ Serosa (rest of GI tract)
What are the features of the mucosa?
Consists of:
- epithelium: simple culomnar type
- lamina propria: loose areolar CT w/ glands, lymph vessels and lymph nodules
- muscularis mucosa: inner circular, outer longitudinal layers of smooth muscle
What are the features of the submucosa layer?
- irregular fibroelastic CT w/ elastic and collagen fibres
- no glands (except in esophagus)
- contains blood and lymph vessles and Meissner’s/ submucosal plexus of nerves
What are the features of the muscularis externa layer?
- inner circular, outer longitudinal layers of smooth muscle
- Auerbach’s/ myenteric plexus of nerves situated between the two layers of smooth muscle
What is the difference between the Serosa and Adventia layer?
Serosa: outermost layer formed by visceral peritoneum
Adventitia: outermost layer formed by CT coat (retroperitoneal)