Salivary Glands Flashcards
What are the 8 functions of Saliva? (1)
Protection:
- Washing action (debris from around the mouth)
- Clearance of sugar (neutralises sugars)
- Lubrication (covers all surfaces)
- Barrier (stops certain substances from adhering)
What are the 8 functions of Saliva? (2)
Buffering:
- Protection from demineralisation (contains calcium and phosphates which help mineralise)
What are the 8 functions of Saliva? (3)
Pellicle Formation:
- Calcium binding
- Also the 1st stage of biofilm formation
What are the 8 functions of Saliva? (4)
Maintenance of tooth integrity
What are the 8 functions of Saliva? (5)
Antimicrobial action:
- Proteins and peptides with antibacterial activity
What are the 8 functions of Saliva? (6)
Tissue Repair:
- Grow factors
What are the 8 functions of Saliva? (7)
Digestion:
- Solubilisation of food substances
- Enzymes
- Moistening and lubricative properties
What are the 8 functions of Saliva? (8)
Taste:
- Solubilisation of food substances
- Proteins that bind to taste substances
What are directions of flow of saliva?
- Secretions from the vestibules over the occlusal surface
- Through the interdental spaces
What are the types of Salivary secretions?
Serous (watery fluid):
- Mainly from the Parotid and submandibular glands
Mucous (mucus; slime)
- Mainly from the Sublingual and minor glands
What as the two salvia concepts?
Whole vs Duct saliva
What’s whole saliva
- Mix of fluids from major and minor salivary glands
- Gingival Crevicular fluid
- Oral bacteria and food debris
What are the Major Salivary Glands?
- Parotid
- Submandibular
- Sublingual
What are the key features of the Parotid gland?
- Pure Serous gland
- In front of the external ear
- Duct = Stensen’s Duct
- Innervation = Glossopharyngeal nerve (IX) (STIMULATES SECRETOMOTOR ACTIVITY IN THE PAROTID SALIVARY GLAND)
- Sensory Innervation = Auriculotemporal nerve - branch of the mandibular nerve (V3) (division of the Trigeminal nerve exists through Foramen Ovale)
What are the key features of the Submandibular gland?
- Mixed acinar cell type: mainly serous (60%)
- Posterior part of the floor of the mouth
- Duct = Wharton’s duct
- Parasympathetic Innervation: Facial Nerve (VII) (STIMULATES SECRETOMOTOR ACTIVITY IN THE SUB.MAN GLAND)
What are the key features of the Sublingual gland?
- Mixed acinar - mainly mucous (75%)
- Posteror part of the gloor of the mouth
- Duct = Ducts of Rivinus
- Parasympathetic Innervation: Facial Nerve (VII) (STIMULATES SECRETOMOTOR ACTIVITY IN THE SUB.MAN GLAND)
What’s the sympathetic nerve supply of the glands?
- Superior Cervical Ganglion
What are the major structures that pass through or deep to the Parotid gland? (Nerve)
Facial Nerve:
- Enters skull via Stylomastoid Foramen then passes through the Parotid gland
- Divides into Upper and Lower branches within the gland
- Branches further into the 5 branches of the facial nerve:
Top
- Temporal
- Zygomatic
- Buccal
- Marginal Mandibular
- Cervical
- Intimate relationship means dissection of the gland is complicated - try not to damage nerves
What are the major structures that pass through or deep to the Parotid gland? (Artery)
- External Carotid Artery enters into or passes deep to the inferior border of the parotid gland
- Continuous in a superior direction; gives off the POSTERIOR AURICULAR ARTERY before dividing into:
- MAXILLARY ARTERY
- SUPERFICIAL TEMPORAL ARTERIES
- Superior Temporal artery branches to give off the TRANSVERSE FACIAL ARTERY
How many Minor Salivary glands are there?
- 600 - 1000 glands
- Similar to major BUT they are SMALLER and have SHORTER DUCTS
What are the characteristics of Minor Salivary Glands?
- Mainly Mucous
- In the Oral Mucosa, they are virtually everywhere except:
1. Gingival mucsoae
2. Alveolar Mucosae - Labial glands
- Buccal glands
- Palatal glands
- Lingual glands
What’s the general structure of Salivary glands?
- ACINI (Secretory End Pieces)
- DUCTS
Look like a bunch of grapes:
- ACINI = GRAPES
- DUCTS = STEM
- CT = AIR SURROUNDING GRAPES AND STEM
What are the structural units of a salivary gland?
Epithelium:
- Secretory end-pieces (Acini)
- Ducts (Intercalated/Striated/Secretory)
- Myoepithelium (on acini/on ducts)
Connective Tissue:
- Capsule
- Septa: Divide glands into (LOBES+LOBULES (SMALLER)
- Surrounds all epithelial units
- Carries: Bloody + nerve supply
What creates the division between Salivary Lobes and Lobules?
- Connective tissue SEPTA
- Lobes = largest units, separated by thick septa
- Lobules = smaller units, separated septa
- Lobules contain Intercalated and striated ducts (intralobular ducts)
When do the Salivary glands begin to develop?
- 6 weeks I.U.L (Parotid)
- Epithelium-Mesenchymal interaction
- Followed by Epithelial proliferation and lobule formation
- Epithelial canalisation and cellular differentiation follow
What are resting secretions?
- Present throughout the day and night
- Keeps the mouth and Oro-pharynx:
+ Moist
+ Lubricated
+ Protected
What’s the typical volume of saliva produced per day?
- 500-750 ml/day
- 90% from major salivary glands
- 10% from minor salivary glands
How do you calculate Flow Rate?
Volume(ml) / minute
- 0.3ml/min at rest (average) = unstimulated flow rate
- 1.75ml/min when stimulated (stimulated) flow rate
What are the sources of Saliva at Rest vs when Stimulated?
Parotid = 10% (R) - 60% (S) Sub.M = 70% (R) - 30% (S) Sub.L = 10% (R) - 5% (S) Minor = 10% (R) - 5% (S)
Acinar Cells: What are they?
- Cells comprising the Acinus (secetory end piece)
+ Involved in saliva production
+ Can be SEROUS OR MUCOUS cells
- Pyramidal shaped which are polarised for function
What are Serous Acinar cells?
- Nucleus at basal part of cell (bottom)
- Basophilic Rough Endoplasmic Reticulum
- Granular appearance
- Cells discharge their secretions into the tubular lumen via intercellular canaliculi running between cells
What are Mucous Acinar cells?
- Pale Cytoplasm - mucins lost or not easily stained
- Flattened basal nucleus
- Many large mucin granules
What are Mucous Acinar + Serous Demilunes?
- Mucous acinus capped by serous cells
- Serous cells discharge via the Intercellular canaliculi between the mucous cells
What are Myoepithelial cells?
- One Acini and Intercalated ducts
- 1, 2, 3 myoepithelial cells in each salivary and piece body
- 4-8 processes
FUNCTION:
- Contractile elements for the acini cells - squeeze them
- Regulate duct lumen diamete
What are the characteristics of the Intercalated ducts?
- Low cudoidal cells
- Large central nucleus
- Difficult to see in routine wax sections
What are the characteristics of Striated ducts?
- Not present in Sublingual glands
- Columnar shaped cells
- Active modification of primary saliva
- Massive basal membrane folding
What are the characteristics of Secretory (collecting) ducts?
- Large lumen
- Pseudostratified columnar epithelium
- Stratified near termination - merges with Stratified squamous oral epithelium
What does the Parotid gland look like Histologically?
- Most compound serous acini
- Large number of ducts
- Adipocytes and plasma cells
What does the Submandibular gland look like Histologically?
- Mainly small Serous acini with some Mucus acini present
- Myoepithelial cells
- Demilunes
- The intercalated and striated ducts are less numerous than those in the parotid gland
What does the Parotid gland look like Histologically?
- Mixed gland but Mucus acini are predominate
- Intercalated ducts are short and difficult to recognise
- Intralobular ducts are fewer in number than in the parotid or submandibular glands
