Salivary glands Flashcards
What happens to saliva composition with age?
Saliva composition changes with age.
Time is a major factor in determining the content and composition of saliva.
This is relevant for understanding the impact of changes in saliva composition with age on oral health. Such as swallowing of food and protection against dental caries.
What are the types of salivary glands based on function?
Serous producing glands
Mucous producing glands
Mixed glands
What are the types of salivary glands anatomically?
3 pairs of major glands:
Parotid, submandibular, sublingual
How common are salivary gland tumours?
Rare but serious
What type of ducts do the major salivary glands have and what kind of saliva do they produce?
Parotid: Watery - serous saliva rich in amylase, proline rich proteins (Stenson’s duct)
Submandibular gland - More mucinous (Wharton’s duct)
Sublingual gland - Viscous saliva (Ducts of rivinus or duct of bartholin)
What kind of epithelium does the floor have?
Non-keratinized stratified squamous epithelium.
What salivary glands should be examined during examination of the oral cavity?
It is important to palpate the major salivary glands during extraoral examination
What are the types of minor salivary glands? Where are they located?
Minor salivary glands are not found within gingiva and anterior part of the hard palate.
Serous minor glands are von ebner glands below the sulci of the circumvallate and folliate papillae of the tongue.
Glands of Blandin-Nuhn located on the ventral surface of the tongue.
Palatine, glossopalatine glands are pure mucous.
Where are serous minor glands located?
Von ebner glands below the sulci of the circumvallate and folliate papillae of the tongue.
Where are glands of Blandin-Nuhn located?
Located on the ventral surface of the tongue.
What cancer is commonly seen in glands of Blandin-Nuhn?
Ventral surface of the tongue
What glands produce the saliva and how much do they contribute?
Most from submandibular (65%)
Smaller proportion from parotid gland (25%)
Lingual gland (5%)
Minor salivary glands produce the remaining (5%)
Total saliva produced per day is approximately 700 - 1200 ml per day
What is the protective function of saliva?
Lubricant (glycoproteins)
Barrier against noxious stimuli
Washing non-adherent and acellular debris
Formation of salivary pellicle (Calcium binding proteins: Tooth protection and plaque)
How does saiiva produce buffering action? Why is this useful?
Phosphate ions and bicarbonate.
Bacteria require specific pH conditions
Plaque microorganisms produce acids from sugars
What are the anti-microbial actions of saliva?
Lysozyme hydrolyzes cell walls of some bacteria
Lactoferrin binds free iron and deprives bacteria of this essential element
IgA agglutinates microorganisms
How does saliva maintain tooth integrity?
Calcium, fluoride and phosphate ions are exchanged with tooth surface
What are the tissue repair functions of saliva?
Bleeding time of oral tissues shorter than other tissues
Resulting clot less solid than normal
Remineralization
Several growth factors have been identified in saliva and contribute to healing process
How does saliva help with taste?
Solubilizing food substances that can be sensed by receptors
Solubilized food has a trophic effect on receptors
How is saliva flow regulated throughout the day?
0.5L/24h secreted mostly at day time
Saliva flow is simulated through neural pathway triggered by foods’ chewing and tasting
Almost no salivary secretion during sleep
What rate of saliva production is considered normal and what is low?
Very low UWSFR<0.1ml/min
Low 0.11 - 0.25ml/min
Normal UWSFR >0.25ml/min
How is UWSFR different between males and females?
Men produce more saliva than females
UWSFR is significantly affected by CPI, OHI-S, and BMI
How are UWSFR and risk factors correlated?
High BMI scores, moderate-to severe gingivitis and low level of oral hygiene
Where does the parotid arise embryologically? When is it first formed?
Parotid is ectoderm in origin (Forms 4-6 weeks of embryonic
life)
Where and when do the sublingual and submandibular salivary glands originate?
Sublingual-submandibular are endoderm in origin
Sublingual and minor glands develop around the 8 - 12 week mark
What do salivary glands arise from? How do they form?
Differentiation of ectomesenchyme
Development of fibrous capsule
Formation of septa that divide the gland into lobes and lobules
What are the types of tissue in salivary glands?
Glandular secretory tissue (Parenchyme)
Supportive connective tissue (stroma)
What are the types of ducts in salivary glands?
Intercalated ducts -> striated ducts -> Major collecting duct
What are the main features of serous glands?
Cytoplasm is dark and has a rough appearance with no lumen
What do mucinous cells look like
Cytoplasm looks clear
Nucleus small
Cells are in a circle bound by tight junctions with a lumen in the middle
What is the difference between primary and secondary saliva?
Primary saliva:
Serous and mucous cells.
Intercalated ducts
Modified saliva:
Striated and terminal ducts
End product is hypotonic
What controls fluid and electrolyte production in saliva?
Parasympathetic innervation
Binding of ACh to muscarinic receptors triggers opening of channels of K+, Cl-, Na+, and
Norepinephrin via alpha-adrenergic receptors triggered by substance P which activates the Ca2+
How are myoepithelial cells arranged on salivary glands?
1, 2, or 3 myoepithelial cells in each salivary and piece body.
4 to 8 processes
Desmosomes between myoepithelial cells and secretory cells
Myofilaments frequently aggregated to form dark bodies along the whole process
What is the potential issue with myoepithelial cells.
Myoepithelial cells are responsible for many cancers such as pleomorphic adenomas
What are myoepithelial cells made up of?
Intercalated ducts are more spindled-shaped and fewer processes
Ultrastructurally very similar to that of smooth muscle cells