An overview of structure and function of Oral Mucosa Flashcards
What is the oral mucosa?
The mucous lining of the mouth
Name parts of the oral mucosa
- Upper lip
- Alveolar mucosa
- Hard and soft palate
- Cheek
- Tongue
- Underside of tongue
- Gingiva
- Floor of the mouth
- Lower lip
What are the differenced between the oral mucosa and the skin
- Oral mucosa is lighter than skin
- Oral mucosa has a constantly moist surface due to secretion of saliva
- Oral mucosa doesn’t have skin appendages such as hair follicles sweat and sebaceous glands.
What are the functions of the oral mucosa?
- Protection again mechanical, abrasive and microbial threats
- Sensation such as touch, taste, thirst and pain
- Secretion from minor salivary glands and limited sebaceous glands
- Absorption of sublingual dissolving drugs
- Thermal regulation (Only in animal)
Name the 3 types of oral mucosa
- Masticatory mucosa
- Lining mucosa
- Specialised mucosa
Is masticatory non keratinised or keratinised?
Keratinised
Is lining mucosa Keratinised ?
no it is non keratinised
Describe specialised oral mucosa
It is Keratinised mucosa with specialised structures called papillae
What do specialised oral mucosa have?
specialised structures called papillae
Give examples of specialised oral mucosa
The dorsal surface of the tongue
Where is lining mucosa found?
- Vermillion border
- Lining of the lips
- Lining of the cheeks
- Ventral surface of the tongue to a certain extent
- Floor of the mouth
Name the 3 general components of the oral mucosa
- Epithelial tissue
- Lamina propia
- Submucosa
What is lamina propia?
The connective tissue component of the oral mucosa
Why is the oral mucosa always moist?
Due to the production of saliva
What are the main challenges the oral mucosa faces?
- Chewing and mastication
2. Chemicals in food
Where is masticatory mucosa found?
Found on the surface of the gingiva and the hard palette
Where is specialised oral mucosa found?
On the upper surface of the tongue
What is the tongue split into?
The posterior 1/3rd and the anterior 2/3rds
Describe the posterior 1/3rd of the tongue
It is full of lymphoid tissues called the lingua tonsils
Describe the anterior 2/3rd of the tongue
It is keratinised mucosa with specialised structures called the papillae that hold taste buds
Describe the general structure of the oral mucosa
Made up of two types of tissues:
- An epithelial tissue coverage
- Supported by connective tissue
What is the connective tissue that supports the epithelial tissue of the mucosa supported by?
Divided into 2 parts:
- Lamina propia that directly supported the epithelium
- Submucosa that contains blood vessels
What does the sub mucosa of the oral mucosa contain?
- Blood vessels
- nerves
- Adipose tissue
What is epithelial tissue?
It is several compact layers fo cells that cover a body surface or line a cavity or hollow organ in the body
What forms the interface between the epithelium and the lamina propia
Is formed of the interlinking between the epithelial rate pegs and the C.T papilla and is demarcated by the epithelial basement membrane
What is the epithelial tissue formed by?
Either the ectoderm, mesoderm or endoderm
What are entrocytes?
They are epithelial cells as they are closely packed together and they line the gut
Name the 2 major classifications of epithelial cells
- Simple epithelial
2. Stratified
What does the word simple refer to when describing epithelial cells
Epithelium formed of one layer of cells
What does the word stratified refer to when describing epithelial cells
Epithelium formed of several layers of epithelium cells
What can we use to further classify epithelial tissue once we have established if its simple or stratified?
We further classify epithial tissue by the shape of its cell eg cuboidal, columnar, squamous etc
Name the different types of epithelial tissues
- Simpe squamous
- Simple cuboidal
- Simple columnar
- Stratified squamous
- Stratified cuboidal
- Pseudostratified columnar
- Transitional epithelium
Describe squamous cells
They are flat
Epithelial tissue made up of one layer of flat cells is called what?
Simple squamous
One layer of cube shaped epithelium cells is called what?
Simple cuboidal
One layer of column shaped epithelium cells is called what?
Simple columnar
What does Pseudostratified mean?
“Fake columnar”
Means the cells are column in shaped and look to be in layers but are not
What is transitional epithelial?
A specialsed type of tissue that lines the urinary tract
Name the 3 different types of epithelial junctions
- Gap junciton
- Tight junciton
- Desmosome
What are Desmosome and where are they found?
They are an adhesive structure found on the basal side of the cell
Describe Stratified squamous tissue
Multiple layers of flat cells
Describe Stratified cuboidal tissue
Multiple layers of cuboidal cells
Describe Stratified columnar tissue
Multiple layers of column shaped cells
Which type of epithelium tissue is the oral mucosa covered by ?
Stratified squamous epithelium
What are Desmosomes formed of?
They are formed of thickening plaques of the cell membrane
There are transmembrane filaments called cadherin found within the plaques
Name the protein that makes up the transmembrane filament of the Desmosome
cadherin
What do demosomes do?
They cross between adjacent cells to tighten them together
What are gap junctions formed of?
They are formed of inter connecting channels between the 2 sides of the cell
Why are gap junctions important?
They allow for the exchange of molecules between the 2 cytoplasms of 2 adjacent cells
What are tight junctions formed of?
Formed of 3 specialised protein structures
What do tight junction do?
Tightens the gap between adjacent cells to prevent leakage of any ions from the cytoplasms
What is a hemidesmosome
Half a desmosome formed from a thickening of the cell membrane and cadherin filaments
Where are hemidesmosomes found?
They are attached to the underlying basement membrane and the extracellular matrix
What allows for the epithelium to be in tight contact with the underlying connective tissue?
hemidesmosomes
What word is used to describe epithelial tissue made up of only one layer of cells?
Simple epithelium
On a histological level give some differences between keratinised and non keratinised tissue
- Keratinised tissue has a thick layer of protein that protects the epithelium
- Non Keratinised epithelium is thicker and made of more layers
Why might non Keratinised epithelium be made up of more layers?
As theres no protective keratin layer the epithelium has to compensate protection by adding more layers of cells
Name the 2 cellular components of the oral epithelium
1, Keratinocytes
2. Non-Keratinocytes
What Do Keratinocytes make up?
They form all the layers of the covering epithelial of the oral mucosa
What are non keratinocytes called and why?
Called dendritic cells because they have extended cellular processes
Name the 4 types of non keratinocytes
- Melanocyte
- Langerhans cells
- Merkel’s cells
- Inflammatory cells
Name the different cell layers the make up the epithelium
- Basal cell layer
- Prickle cell layer
- Intermediate layer
- Surface layer
Name the different cell layers the make up the epithelium
- Basal cell layer
- Prickle cell layer
- Intermediate layer
- Surface layer
What is the function of basal cell layer?
Only function is to regenerate the epithelial tissues
What is the basal cell layer sometimes called?
Germinating cell layer
Why does epithelial tissue need to be regenerated?
Epithelial tissue is readily squamated due to mastication so needs to be regenerated
Which epithelial cell layers are similar in both keratinised and non keratinised tissue
The basal cell layer
What are the differences in the prickle cell layer between keratinised and non keratinised tissue
The keratinised layer has a lot of tono filaments that are bundled into fibre the non keratinised layer only has dispersed tono filament NO fibres
What are the differences in the intermediate layer between keratinised and non keratinised tissue
- In keratinised tissue this layer is called the granular intermediate layer as it has granules
2, Non keratinised tissue is made up of multiple layers and has no granules but contains membrane bound organelles that contain glycogen
What do the granules in the intermediate layer of keratinised contain?
They contain hyaline keratin (Keratohyalin)
Describe the non keratinised intermediate cell layer
Made up of multiple layers
Contains membrane bound organelles that contain glycogen
Describe the intermediate layer of keratinise tissue
It is called the granular keratinised layer as it has granules that contain hyaline keratin (Keratohyalin)
It is also single layered
What is the surface layer of keratinised tissue called
The keratinised surface layer
What happens to cells as they fill with keratin?
They die and form a fortified layer of keratin
What happens to cells as they fill with keratin?
They die and form a fortified layer of keratin
Describe the non keratisinsed surface layer?
Maintains its nucleus
Less mature than keratinised surface layer
No surface organelles
Name the 2 stages of keratin maturation
- Ortho-keratin
2. Par- keratin
Describe Ortho-keratin tissues
Has no nuclei in the superficial layer
Describe Par- keratin tissues
Remenants of small nuclei can be seen in the superficial layer
What is the mature keratin tissue layer called
Ortho-keratin
Name the 3 major non keratinocytes found in the surface layer of no keratinised epithelium
- Langerhan cells
- Merkel cells
- melanocytes
What is the common feature between langerhan cells, Merkel cells, melanocytes
They are all dendritic cells
What function do langerhan cells have?
They have an immune/ defence function as they are antigen printing cells
What function do Merkel cells have?
They have a pigmentation function as rehydrates synthesis melanin
What function do melanocytes have?
They have a sensory tactile and allow for tactile sensation
Where are Merkel cells found?
They are found in the basal cell layer connected to a Merkel disk that is attached to an afferent sensory nerve
What is the submucosa formed of?
2 layers:
- Lamina propia
- Submucosa
What is the lamina proper formed of?
Formed of the interdigitation of the epithelium with the underlying connective tissue
What are the finger like structures extended by the epithelium called?
Epithelial Rete Pegs/ ridges
What is the connective tissue that extends into the Rete pegs called?
Connective tissue papillae
Name the 2 layers that make up the lamina propia
- Papillary layer
2. Reticular layer
Describe the papillary layer of the lamina propia
It is made up of loose connective tissue
Has finger like projection called Rete Pegs/ ridges
Describe the reticular layer of the lamina propia
Made up of dense connective tissue
Name the cells that make up the lamina propia
- Fibroblasts
- Endothelial cells
- Macrophages
- Mast cells
- Lymphocytes
What do fibroblasts do?
They synthesis fibres and extracellular matrix
Where are the Endothelial cells found
They line the blood vessel
What do macrophages do?
Phagocytosis and antibody presenting
Describe mast cells
Contain histamine and heparin
What do lymphocytes do ?
They increase during inflammation
What are histiocytes?
They are macrophages before they are activated
What are macrophages called before they are activated?
They are called histiocytes
Describe the structure of the lamina propia
- Cells
- Fibres
- Extracelular matriz
- Blood supply and sensory nerve supply
Which fibres make up the lamina propia
90% collagen type I
8% Collagen type III
2% non-collagenous fibres
Name some non-collagenous fibres
- Elastin
2. Oxytalan
Describe the extracellular matrix that makes up the lamina propia
Hydrates gel of glycoproteins and proteoglycans
Name the 2 layers that form the basal lamina
Lamina lucida
Lamina densa
What is the lamina densa made up of?
Formed of dense plaque
What connects the cells of the basal lamina to the basement membrane ?
hemi-desmosomes
How is the basement membrane connected to the lamina propia
By anchoring fibres
Describe anchoring fibres
They are loops of collagen 6 that connects the basement membrane and the lamina propia
What can happen If the anchoring fibres are damaged?
Can lead to immunodeficiency disorders
Describe the submucosa layer
It is made up of blood vessels nerves and the minor salivary glands
Name the different types of papillae we can find on the tongue
- Fililform papillae
- Fungiform papilla
- Foliate papila
Describe Fililform papillae
They are pyramidial highly keratinised and cover the whole surface of the tongue
What happens if the Fililform papillae are overgrown?
Can lead to hairy tongue which can harbour bacteria and fungi
Describe Fungiform papillae
Contain taste buds
