oral mucosa 1 dr: 3mmar
TRANSCRIPT
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Oral mucosa( lecture 1 )
Contents of chapter:- 1) definition. 2) functions. (protection , sensation , secretion). 3) organization. (outer vestibule & oral cavity proper). 4) classification. (masticatory & lining & specialized). 5) histological str. (oral epith.,lamina propria , basement memb)
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Oral mucosa: (epith + C.T) its structurally , functionally transitional zone between the skin & GIT , exhibits features of both.
its like GIT in : its bathed in fluid & have high rate of turnover. like skin in : its possesses a stratified epith. Which
is keratinized in many places thus prevents , limits diffusion across both direction.
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skin Oral mucosanot moist moisture
sebacious salivary glands
found not Hair follicle
more less firmness
less more Surface smoothness
less deeply colored color
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Human tissues
1 )epithelial
3 )mascular
4 )nervous
2 )connective
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General features of epithelial tissue:
1) cells rests on basement membrane. & have free surface
2) cells adhere to each other in one layer or more. 3) cells a-vascular but have nerve fibers. 4) cells cover a surface , lined cavity and form glands. 5) basal surface contact the basement membrane while free surface interface with external environment or space within the body.
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Oral mucosa has 2 main tissue component: 1) stratified squamous epith. (oral epith.). 2) underlying C.T layer (lamina propria).
rete-pegs: part of oral epith. Which interdigitate with C.T papillae.
connective tissue papillae: irregular upward projection of C.T which inter face with rete-pegs.
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Functions of the oral epithelial:-(protection , sensation , secretion ). 1) protection: a- separates ,protect deeper tissues & organs in oral region from the environment of oral cavity. b- its show number of adaptation of epith , C.T to withstand force of mastication & it acts as barrier to microorganism , toxins.
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2) sensation: its provide information about events in oral cavity where as lips , tongue perceive stimuli outside the mouth.
a) in the mouth receptors respond to temperature , touch , pain , taste and thirst . b) tongue has taste buds. c) reflexes (swalloing , salivation , gagging) are initiated by receptors in the oral cavity.
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3) secretion: major secretion associated with oral mucosa is saliva from major , minor salivary glands which maintains a moist , lubricant surface of the oral mucosa . ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ
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3-organization: 1) outer vestibule bounded by lips , checks.
2) oral cavity proper : superior zone of oral cavity proper formed by hard & soft palate. inferior border formed by floor of mouth , tongue.
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4-classification of oral mucosa: (25%masticatory mucosa & 60%lining mucosa & 15%specialized mucosa).
1) masticatory mucosa: (25%) this parts from oral mucosa subjected to force of mastication & pressure this parts are : 1-Gingiva 2-Hard palate. *) this parts are rubbery , resistant & keratinized or para-keratinized stratified squamous epith.
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2)Lining mucosa (60%): its presen in areas which not subjected to high force but its must be mobile , distensible .
1.2.3- Its buccal , labial , alveolar mucosa 4.5- floor of mouth & ventral tongue 6- Soft palate.
Its non keratinized stratified squamouth epith.
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specialized mucosa (15%):its mucosa covering the dorsal surface of the tongue and contains different types of taste buds , papillae and lingual tonsils , lymph tissues.
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5) Histological structure:
Basal cell layer
Prickle cell layer
Granular cell layer
Cornified cell layer
basal
intermediate
superficial
3-Lamina propria
Stratified squamous epithelium
KeratinizedNon-
keratinized:
•ortho-keratin.•para-keratin.
Papillarylayer
Reticular layer
glands or
fat cells
May or
may not be
present
1-Oral epithelium
4-
Submucosa
Basement
membrane
2-basement membrane
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Histological structure: (oral epith. & lamina propria & basement membrane in between &
sub-mucosa )ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ
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1) Oral epithelial: its ectodermal in origin formed of stratified squamous epith which is keratinized in some areas & Non-kerarinized in others.
N.B: stratum = layer
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Non-keratinized epith. Keratinized epith.
Stratum basale Stratum basale (basal layer)
Stratum spinosum Stratum spinosum (prickle)(prickle layer)
Intermediate layer Stratum granulosum(granular layer)
Superfacial layer Stratum corneum (keratinized layer)
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Keratinized Epithelium Nonkeratinized Epithelium
Oral epitheliu
m
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1) Keratinized epithelium: this type found in areas which subjected to force like gingiva , hard palate (masticatory mucosa).
N.B: cells which form this layer called keratocytes or keratinocytes.
*Cells are arranged in 4 layers (basal & spinous & granular & cornified). the names of layers derived from their morphology.
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Layers of keratinized epith (basal&prickle&granular&cornified).ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ
ــــــــــــــــــــــــــــــــــــ1)Basal layer: 1. its single row of columnar or cuboidal cells that is closely attached to
each other & arranged on basement membrane.
2. Cells posses all usual organelles & tonofilaments (tonofilaments: its fibrous protein synthesis by ribosomes , seen as long filaments chemically its cytokeratin ).
3. Its site of cell division since its divided into 2 cells (progenitor cells , mturative cells)
*progenitor cells: remain in base to divide again. *maturative cells : migrate toward the surface.
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2) Spinous cell layer: 1. Its consist of several rows of polyhedral cells of different shapes , size.2. Spinous layer & basal layer constitute more than half thickness of the epith.3. Cells joinded together by intercellular bridges giving the cells prickly apperance.4. Wide inter cellular space compared with Non-keratinized epith.5. Its most active cells in protein synthesis.6. Numerous , well developed organelles.7. No sudden changes in appearance of cells & there is gradual
decrease in synthetic activity through the layer.8. In the upper part of this layer there are odland’s bodies .
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odland’s bodies: (keratinosomes or membrane coating granules).• Its present in superfacial layer of prickle layer or in first layer of granular layer• Its may originate from golgi complex.• This granules discharged in intercellular space, act as barrier to penetration of
forgein substance.• Its responsible for thickning of cell membrane.
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3.Granular cell layer: 1. Its several rows of flattened epith. Cells.2. Many organelles are reduced , cytoplasm will be occupied
by tonofilaments & tonofibrilis.3. Cells contains large number of small granules called
(keratohyaline granules).4. Odlands body discharge into inter-cellular space which act
as barrier & increase the thickness of epith.
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4.Cornified layer: 1. Its present in keratinized epith as final stage of
maturation.2. Cell loss all organelles & filled by closely packed
tonofilaments which are surrounded by matrix protein
and this structure called keratin.3. Its shed (process of desquamation).4. Weak desmosomes to allaow desquamation.5. Its provide mechanical , chemical protective function to
the mucosa.
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2. Non-keratinized epith.: (in this type there absence of cornified & granular cell layer).
1. Epith. Is thicker , outer half of epith. Shows changes which distinguished them from basal , prickle cells.
2. Outer half divided into 2 zones (intermediate , superfacial layer).
3. This cells increase in size and there is accumulation of glycogen , presence of keratohyaline granules which appear more regular & not associated by tonofilaments.
4. cells of Outer 2 strata are tightly packed together thus intercellular space nearly absent.
5. Cells of stratum intermedium contains odlands body with there size , shape , location differ from those found in keratinized epith.
6. Super facial layer contains nucleus , few organelles.
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Thanks
Dr:3mmar