Week 11 - Salivary Glands Flashcards
What are the function of saliva?
speech, mastication, swallowing, taste, digestion, protection, buffering, antimicrobial action, maintenance of tooth integrity, soft tissue repair
What protein is involved in taste?
gustin that is necessary for growth and maturation of taste buds
What is digestion due to?
salivary amylase that functions in degrading starch
What does protection do?
lubrication protects lining mucosa from noxious stimuli, bacterial toxins, and minor trauma
How does lubrication with protection work?
- Washing action to rid mouth of non-adherent bacteria
- Clears sugars from mouth
What is the function of buffering?
prevents potential pathologic bacteria from colonizing the mouth, most require a specific pH
What exactly gets buffered?
Buffering of microbial acids (bicarbonate and phosphate ions)
What does sialin protein do?
protein that raises pH of dental plaque after exposure to fermentable carbohydrates to even things out
What are things involved in antimicrobial action?
Lysozyme
Lactoferrin
Salivary IgA
What is the function of lysozyme?
Hydrolyzes bacterial cell walls
What is the function of lactoferrin?
binds free iron and thereby deprives bacteria of an essential nutrient
What is the function of salivary IgA?
causes bacterial clumping (agglutination)
What is the maintenance of tooth integrity?
calcium and phosphate ions facilitate mineralization of tooth surface
How is there soft tissue repair?
via Epithelial growth factor and clotting factors
What are ectomesenchymal cells?
undifferentiated cells that cause invagination of oral epithelial cells
What do ectomesenchymal cells dictate?
differentiation of oral epithelium which, in turn, proliferates and grows into the underlying mesenchyme
The epithelial buds undergo histo-differentiation and morpho-differentiation to form assemblies of:
- Alveoli that develop into acinar cells (form serous, mucous or sero-mucous product)
- Serous: water based
- Mucous: contains protein mucin
- Sero-mucous: combination
- Epithelial cords that develop into salivary ducts
What are the stages of salivary gland development?
- Induction of oral epithelium by underlying ectomesenchyme (initial invagination of cells)
- Growth of the epithelial cord (eventually becomes duct)
- Initiation of epithelial cord branching
- Repetitive branching and lobule formation
- Canalization of the presumptive ducts (apoptosis occurs to make ducts hollow)
- Cytodifferentiation of the ducts at the tips to become acinar cells, myoepithelial cells (small muscle cells), and ductal cells
What does Cytodifferentiation of the ducts at the tips done with the help of?
FGF (fibroblast growth factor) and EGE (epidermal growth factor)
What is the development process of salivary glands? what do they differentiate into?
FGF and EGF act on terminal bulb cells (undifferentiated cells) that can differentiate into
1. Acinar cells
2. Myoepithelial cells
3. Duct cells
What is the process timeline of the development process?
6th week of development for parotid and submandibular gland
8th week of development for sublingual gland
10th week of devepopment for minor salivary glands
What are myoepithelial cells?
envelope acinar cells. They are smooth muscle contractile cells that help with secretory process. Contract and squeeze mucous contents into the gut
What are ductal cells?
Intercalated duct (tends to have myoepithelial cells present) -> striated duct -> collecting duct (take salivary fluids to destination)
Describe the appearance of glands
lobular in appearance and contain septa that form borders of lobules
What is the hierarchy of ducts
Intercellular canaliculus
Intercalated duct
Striated duct
Excretory duct (aka collecting duct)
Terminal excretory duct
What are intracellular canaliculus?
In between acinar cells. Contain villi.
Water passes freely throughout the membrane and proteins are secreted and exchanged in granule forms
What are intercalated ducts?
Lined with cuboidal cells. Unknown function
May have backup function, stem cells to replace acinar cells
What are striated ducts?
Striated duct Have microvilli involved in electrolyte resorption
Na and Cl: resorbed
K and bicarbonate: secreted into duct
Location where EGF is secreted to help with differentiation of terminal bulb cells
What are excretory duct/collecting ducts?
Smooth duct with flat cells and no villi
What are the three major salivary glands?
consist of parotid, submandibular, and sublingual glands
Where does parotid gland exit out of?
Stenson’s duct
Where is the parotid gland near?
1st and 2nd max molars