Online Lecture Week 7: Tissues Working Together 3: Oral Mucosa 2

Recap:

Masticatory Mucosa is a keratinised stratified squamous epithelium.

Found on the hard palate, attached gingiva, dorsum of tongue. It is an area with lots of mechanical exposure to abrasion and physical, thermal or chemical damage. Therefore exhibits distinct resistance to deformation under load.

Masticatory Mucosa has an increase in the depth of the connective tissue papillae (protrusions) on the surface interfact between the epithelium and laminate propia. This allows for a high level of strength and resistance due to more hemidemosomes + more surface area.

Lining Mucosa is a non-keratinised stratified squamous epitheloum.

Found everywhere else.

TONGUE:

The tongue is a type of specialised oral mucosa. It is a striated muscle, that has bundles which run in 3 planes. This allows the tongue to move in all directions, and change shape.

Characteristics:

Non-keratinised around the lateral and lower regions
Keratinised around the upper region of tongue
Has filliform keratinised papillae
Light keratinised fungiform
Foliate
Circumvallate

Ventral surface of tongue:

Non-keratinised stratified squamous epithelium

Dorsal Surface of tongue:

Lingual Mucosa
Keratinised stratified squamous epithelium
Numerous surface specialisations
- Papillae
- Taste Buds
- Lingual Glands, Produce Serous Secretiond

Tongue Surface Specialisations:

Fungiform has taste buds on dorsal surface
Specialised sensory receptors on lateral sides of circumvallate
Microvilli on the surface of sensory cells
Basal Cells, which replicate/repair, differentiate into support + sensory cells
Nerve + Synapses

Taste Buds:

Found in fungiform and circumvallate papillae, not filiform
Widely scattered on tongue (dorsal + lateral surface)
All involved in action potential to receive taste.

There is neurosensory epithelial structures embedded in the surface epithelium of fungiform and circumvallate papilla.

These appear as onion-like, oval, pale staining structures.

Extends through the full thickness of the epithelium, and opens on the surface through a taste pore.

Taste Buds Have:

Receptor cells
- Modified epithelial cells with microvilli
- Protrudes through taste pore
- Increases plasma membrane surface area
- Simulates depolarising action potential, promoting neurotransmitter release
Supporting Cells
Basal Cells

Taste buds also have chemoreceptors, found in oral cavity, uvula, epiglottis and throat.

Most are on the dorsum of the tongue

Types of Papillae:

Filiform papilla; most numerous, conical with keratinised tips, no taste buds.
Fungiform papilla; mushroom shaped, highly vascularised connective tissue core, taste bunds present.
Circumvallate papilla: surrounded by a circular trench, openings of ducts of serous glands.
Foliate papilla: not well developed in humans.

Buccal Mucosa (Lining)

The peaks of the papilla protrusions are not sharp, just more wavy. This means the dermal-epidermal junction is not firmly adhered, which can contribute to the overall flexibility and resilience of the buccal mucosa in response to mechanical stress during activities such as chewing.

LIPS:

Lip Appearance:

The vermilion border is thinly keratinised (reddish)

Lip colour is mainly caused by capillaries + thickness of epithelium and keratin + protein.

Labial Mucosa has a non-keratinised epithelium

Thin skin is keratinised as well, but less thick.

Oral Mucosa comparison with Skin:

Deeper colour (Vascular pigment)
Moist surface
Smooth surface, except in tongue papillae, hard palate
Absence of hair
Sebaceous gland
- Limited distribution in oral tissues
- Not associated with hair follices
Lower inflammatory response

Skin contains the:

Epidermis
Dermis
Hypodermis

Oral Mucosa has:

Oral Epithelium
Lamina propia
Submucousa/Bone

Differences in wound healing:

Oral Mucosa healing is

Rapid (4x Faster than Skin)
Relatively minimal to no scar formation

Oral mucosa has a faster epithelial cell migration speed (higher turnover rate)
Less inflammatory response

Reduced cytokine types that promote scar development

Fibroblasts in higher numbers and activity

Less blood vessels are formed from existing ones, so less inflammation.

Components:

Epithelium
- Physical/mechanical, Chemical, Cellular Protection
Lamina propia (Underlying CT)
- More cellular > cells, blood vessels, neural elements + fibres in the AGS.
- Has a loose papillary layer. Less dense, above reituclar layer
- Has a dense reticular layer. Deeper tissues
Muscularis Mucosa
- Only present in GIT, not in oral tissues

Compare and contrast the structure of the mucosa compared with other lining epithelia (e.g., skin).

Oral Mucosa comparison with Skin:

Deeper colour (Vascular pigment)
Moist surface
Smooth surface, except in tongue papillae, hard palate
Absence of hair
Sebaceous gland
- Limited distribution in oral tissues
- Not associated with hair follices
Lower inflammatory response

Skin contains the:

Epidermis
Dermis
Hypodermis

Oral Mucosa has:

Oral Epithelium
Lamina propia
Submucousa/Bone

LEARNING OBJECTIVES

Identify & describe the LM structure of the different regions of the Lips. [structure and
functional differences bewteen skin, transitional, vermillion & labial zones.]

Specialized oral mucosa, primarily found on the tongue's dorsal surface, is characterized by the presence of papillae and taste buds, which are crucial for taste sensation. Structurally, it is a stratified squamous epithelium, keratinized or non-keratinized depending on the location, and supported by a lamina propria.

Identify and describe the structure and function of the different regions of the lips (i.e., skin, transitional, vermillion, and labial zones).

Understand the functional reasons for regional variation in the function of the masticatory and lining mucosa - epithelium - connective tissue interface.

Lining Oral Mucosa has a:
- Non-keratinised epithelium
- Flexible and expansive laminate propia with elastic fibres, allowing for flexibility and stretching
Masticatory Oral Mucosa has a:
- Keratinised epithelium
- Compact laminate propria and adheres to the bone.
- It is an area of repeated mechanical exposure/physical damage, which is why it has keratinisation and exhibits resistance to deformation under load.
- A specialised mucosa on the dorsal surface of the tongue which is inflexible, tough, resistant to abrasion, and tightly bound to the laminate propia through hemidesmosomes for tighter adherence.
- Covered by a layer of keratinised cells. It is an area of repeated mechanical exposure/physical damage, which is why it has keratinisation and exhibits resistance to deformation under load.
Describe the structure and functions of the specialised mucosa of the tongue (i.e., epithelium and different types of lingual papillae).

Filiform papilla; most numerous, conical with keratinised tips, no taste buds.
Fungiform papilla; mushroom shaped, highly vascularised connective tissue core, taste bunds present.
Circumvallate papilla: surrounded by a circular trench, openings of ducts of serous glands.
Foliate papilla: not well developed in humans.
Understand the structure and function of taste buds and their supporting tissues.