Concise and easy to access notes on oral biology for first year dental students.
Covers oral mucosa, salivary gland physiology, saliva & stimulation of salivation, control of swallowing & mastication, smell and taste.
Oral Mucosa
Oral Mucosa
• Oral epithelium + underlying lamina
propria
• Stratified squamous epithelium
• Rete Processes: epithelial extensions
projecting downwards into underlying
connective tissue
• Connective Tissue Papillae: upward
projections in between rete processes
Specialised Mucosa
• Covers dorsum of anterior 2/3 of tongue
Masticatory Mucosa
• Covers hard palate & gingiva
• Greater SA contact between epithelium & lamina propria
• Lamina propria forms continuum with periosteum – mucoperiosteum (no definite submucosa)
• Stratum basale: short columnar / cuboidal cells, contains stem cells, attaches to lamina propria at
basal lamina via hemidesmosomes
• Stratum spinosum (prickle): polygonal cells, larger than basal cells, larger nuclei than basal cells,
nuceloli appear, prickle spines visible (microscope artefact)
• Stratum granulosum: contains fine, basophilic keratohyaline granules within cytoplasm, cells
flatten, nuclei enlarge/elongate, organelles are lost
• Stratum corneum: most organelles are lost, cells are flattened with a tightly packed appearance
Lining Mucosa
• Covers buccal mucosal sulcus, labial mucosa,
ventral tongue surface, floor of mouth & soft palate Masticatory Lining
• No keratohyaline granules Basal Basal
• Submucosal layer consisting of fat, skeletal muscle Prickle Prickle
and minor salivary glands Granular Intermedium
• Stratum basale & stratum spinosum present, as in Cornified Superficial
masticatory mucosa
• No keratinisation, so no granular layer → stratum
intermedium
• Orthokeratinised Epithelium:
• No keratin on surface, so no cornified layer → cell nuclei disappear in
superficial layer keratinised layer
• Parakeratinised Epithelium:
Non-Keratinising Cells flattened, condensed nuclei
• Langerhan’s cells: found in stratum spinosum remain in cell cytoplasm
• Merkel cells: found in basal layer of gingival • Cornified Envelope: highly
epithelium, may function as touch receptors cross-linked layer of proteins in
• Melanocytes: melanin-producing cells in basal stratum corneum
layer of gingival epithelium
, Salivary Gland Physiology
Salivary Glands
• Exocrine; secrete onto mucosal surfaces of mouth
• Acinar cells: produce saliva, contain secretory granules
• Myoepithelial cells surround and stabilise acinar cells
• Parotid Gland: produces lots of amylase → serous secretions
• Submandibular Gland: produces amylase & mucous → seromucous secretions
• Sublingual Gland: produces lots of mucous → mucous secretion
• Minor Salivary Glands: present in most submucosal surfaces, secrete via main excretory
ducts of oral mucosa
Actions of Sympathetic NS
Formation of Primary Saliva • Causes most protein secretion
Parasympathetic: • Contracts myoepithelial cells
1. ACH binds to M3 receptor on acinar cell • Denervation → some gland
2. Intracellular [Ca] increases via inositol phosphate atrophy
mediators • Sends secretory signals to
3. Apical Cl channels open → Cl- moves out of cells submandibular and parotid
into lumen glands only
4. Na+ moves into lumen through tight junctions
down its gradient
5. H2O moves into lumen down osmotic gradient Actions of Parasympathetic NS
6. Na+, K+ and Cl- move into cell via a cotransporter • Causes most fluid secretion
Sympathetic:
• Contracts myoepithelial cells
1. NA binds to -adrenergic receptor on acinar cell
• Denervation → gland atrophy
2. Intracellular [cAMP] increases via Gs and
• Sends secretory signals all major
adenylyl cyclase
salivary glands
3. Exocytosis of proteins at apical membrane
• Vasodilation as part of secretory
4. NA also binds to -adrenergic receptors,
process
secreting small amounts of H2O and ions
Modification of Primary Saliva
• Resting/unstimulated (low flow rate) → striated ducts remove Na/Cl and secrete K
• Stimulated (high flow rate) → straited ducts remove Na/Cl and secrete K/HCO3-
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