oral mucosa Flashcards
What is the oral mucosa
-membrane that covers entirety of oral cavity
-vast tissue
-upper lip, lower lip, gums, floor of mouth, tongue, hard palate, cheeks
The Functions of the Oral Mucosa
o Protection – against mechanical (due to mastication), abrasive and microbial threats (saliva all the time)
o Sensation (neuroreceptors embedded under mucosa)–touch, temperature, taste, thirst and pain
o Secretion – minor salivary glands and limited sebaceous glands
o Absorption – sublingual (applied under tongue) dissolving drugs
o (Thermal regulation – only in animals e.g. when panting, not humans)
difference between oral mucosa and skin
- colour-oral mucosa lighter
- moisture- oral mucosa has constantly moist surface due to secretion of saliva
3.appendages- oral mucosa doesn’t have skin appendages such as hair follicles and sweat glands
types of oral mucosa
- masticatory (keratinised)
- lining
3.specialised (keratinised)
masticatory
-keratinised
In gingiva (gums) and hard palate
-has extra protective layer called keratin which helps protect mucous membrane and underlying structures from masticatory forces
lining mucosa
non kartinised
Lip (labial), cheek (buccal), floor of mouth, under surface of tongue
-not keratinised as not subject to masticatory forces
specialised oral mucosa
keratinised
Surface of tongue,
-anterior 2/3 has specialised mucosa (has structures called tongue papillae, some which have taste buds), keratinised due to mastication forces
-posterior 1/3 covered with oral mucosa and full of lymphoid tissue-called keratinised
tissue components of oral mucosa
- Covering epithelial tissue
- Supportive lamina propria (connective tissue)
Submucosa (absent at certain sites)
- Supportive lamina propria (connective tissue)
What are epithelial tissues
Closely packed layers of cells that cover surface of body/line cavity of body
types of epithelial tissue
Simple (one layer)
Stratified (2 layers)
types of attachment between epithelial cells
-hemidesmosome
-gap junction
-desmosome (thickening of cell membrane on each side of cell)
-adherens junction (transmembrane protein)
-tight juction
look at pic
What is oral epithelium made of
-Oral epithelium made of stratified squamous (flat) epithelium
-2 types keratinised (gum/palate)/non-keratinised (cheek)
What are keratinocytes?
-found in outermost layer
cells of keratinised epithelium, Cells that form majority of epithilium coverage of oral mucosa, have cytokeratin in them and they form keratin
Non keratinocytes:
Cells of the non-keratinised epithelium,Fewer in number, have specialised function, don’t have cytokeratin/synthesise keratin
What is difference between keratinised and non keratinised tissue?
Non keratinised cells are thicker and have more layers
Keratinised:
Basal layer
Smaller size on for non keratinised
-mainly cuboidal
-basal layer made up of stem cells (do mitosis and cell division as they generate all layers of epithelium
keratinised Prickle cell layer:
shrink and desmosomes more apparent so appears prickly
-in keratinised=bundles of tonofilaments and tonofibrils, in non-keratinised only dispersed tonofibrils
keratinised Granular cell layer
in keratinise, as contains more tonofibirls, contains granules that hold the hyaline keratin in it
Keratinised surface layer
Cells filled with keratin, organelles start shrinking till cell completely keratinised and lose all organelles, become dead and part of keratin layer
Non keratinised layers
-after prickle cell layer, there is intermediate layer as not granular, no granules of keratin but have membrane coated bodes, have glycogen in them
Surface layer-as they mature, have less organelles but retain cell nucleus and some cell organs
non keratinocytes
- langerhans: immune/defence: antigen presenting
- melanocyte: pigmentation: synthesis of melanin. More active in ppl with darker skin, melanin secreted within epithelia to give palate darker colour
- Merkel: sensory: tactile sensation- touch stimulus felt here
structure of lamina proprietary
-Supportive connective tissue made of connective tissue
-lose connective tissue forms papillary layer under epithelium
-interlinked with superficial rete pegs
-papillary layer on top, reticular layer on bottom
-full of fibres
What is basal lamina
-Interface between lamina propria and epithelial tissue
-Connect cells to each other, hemidesmosomes are half desmosomes connect basement membrane (membrane that basal cells sit on) to lamina propria. This is on lamina lucida (transparent area)
-layer under is lamina dense-collagen fibres from lamina propria form lops of fibres that attach basement membrane to connective tissue (made of collagen type 6)
-any defect in this d=structure can cause diseases
What are epithelium rete pegs?
Epithelial extensions that project into underlying connective tissue
Structure of submucosa
-present in almost all mucosal tissues
-Mainly made of connective tissue that contains fibres, blood vessels, nerves, minor salivary glands, fat tissue
papillae
keratinised mucosa with sepecialised structures called papillae, some of which have taste buds
What is tongue papillae
-Tiny bumps called papillae give the tongue its rough texture
-contain taste buds
-4 types
-filiform papillae-major anterior surface of tongue, Pyramidal shaped, completely keratinised, mainly mechanical function, for protection
-fungiform-embedded between filiform papillae, look like mushrooms, keratinised, hgihly vascularised, contain taste buds
-foliate-square shaped, resemble leaf shapes, has taste buds on side, non kertinised
-circumvallate papillae-many taste buds on sides and openings of glands of ebner
Taste buds
-onion like structure, placed on papillae of togue, present in soft palates
-these cells perceive anything we eat/drink and send sensation to afferent nerve to brain
junctions in oral mucosa
-Junctions between diff parts of epithelium e.g. between skin and vermilion border of lip
-Always intermediate layer in-between
-junction between vermillion border of lip and epithelium of labial lining of tongue
-border is keratinised but keratin form/type is diff between skin and vermilion border, they merge into non keratinised epithelium that covers labial lining mucosa
-mucogingival junction=junction between gingiva and mucosa that covers the bone alveolus
cells in lamina propria
fibroblasts
endothelial cells
inflammatory cells
firbosblasts
synthesis of fibres of extracellular matrix
endothelial cells
lining of blood vessels
inflammatory cells
- macrophages-phagocytes (contain lysosomes) and antibody presenting
- mast cells-contain histamine and heparin (allergy/inflkammartion)
- lymphocytes- increase during inflammation
structure of lamina propria
-fibres
-extracellular matrix
-blood supply, sensory nerve supply
fibres
90% collagen, 8% collagen type III, 2% non-collagenous fibres
extracellular matrix
hydrated gel of glycoproteins and proteoglycans
