Week 7: Tissues Working Together 3: Oral Mucosa

Recap:

Mucous Membrane is a moist lining of body cavities that communicate with the exterior.

I.E. Oral cavity, nasal passages, Pharynx, GIT, UGT

What does it do?

  • Lines various cavities/lumens in the body

  • Covers internal organ surfaces

  • Protects underlying tissues from dehydration, pathogen entry + particulate matter.

  • Moist lining secretes moist mucous type lining to trap pathogens + particulate matter.

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

Oral mucosa:

It is a mucous membrane

Characteristics:

  • Structurally resembles skin

  • Similar to other mucous membranes

  • Very different from the GIT mucosa though.

Functions:

  • Protection:

    • Mechanical role, preventing friction/abrasion (Epithelium), preventing compression/shearing (laminate propia which has collagen/elastin)

    • Barrier role against molecles and microorganisms (Epithelim)

  • Sensory

    • Taste (Epithelium Taste Buds)

    • Touch, Temperature, Pain (Epithelium and laminate propia which have sensory receptors)

  • Synthesis/Secretion

    • Saliva (Minor salivary glands in lamina propia, submucosa)

    • Sebum (Sebaceous Glands in laminate propia)

  • Esthetics

    • Vermilion Border of Lips


2. Compare & contrast the structure of a mucosa compared with a different type of lining epithelium eg
the skin




Types of Oral Mucosa:

  • Specialised Mucosa (15% of Total Mucosa)

  • Lining Mucosa (60% of Total Mucosa)

  • Masticatory Mucosa (25% of Total Mucosa)

Lining vs Masticatory Mucosa

  • Both have a stratified squamous epithelium

  • Masticatory lamina propia is much more compact + adheres to the bone

  • Lining mucosa laminate propia is more expansive

Lining Mucosa is present on the

  • lips, buccal mucosa, alveolar mucosa, soft palate, ventral surface of the tongue, and floor of mouth

  • Epithelium is usually nonkeratinised

Masticatory mucosa is found on the:

  • Hard palate, gingiva regions.

  • Has 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.

What is below the mucosa?

Submucosa:

  • This is found in the cheeks, lips, hard palate.

  • It contains adipose/glandular, nerves, blood vessels.

Also direct attachment to bone in some places:

  • Such as oral mucosa, gingiva, parts of hard palate

  • Direct to periosteum

  • No submucosa

  • Firm inelastic attachment through desmosomes, hemidesmosomes, tonofilaments, gap + tight junctions

  • Has papillary folds, which increase surface area for attachment of mucosa to the laminate propia.

Types of Keratinisation:

Keratinisation:

  • Orthokeratinisation

    • A normal keratinised epithelium

    • Present in skin or outer part of lip

  • Parakeratinisation

    • Present in oral cavity (gingiva)

    • If it happens outside of oral cavity it is considered a pathology

    • Cell nuclei is present in keratinised layer (stratum corneum)

Non-Keratinisation:

  • In buccal Mucosa.

Learning Objectives:


What is a mucosa?

The mucosa is a layer of tissue that lines the internal body cavities that lead to the exterior. It covers the surface of internal organs, protecting underlying tissues from dehydration, pathogen entry + particulate matter.

What are the structural and functional differences between lining mucosa and masticatory mucosa?

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.

How does the mucosa function as a barrier?

The mucosa has the three components. Specifically, the epithelium acts as a PHYSICAL barrier against molecules and micro-organisms.

Sensory receptors which detect the presence of dangerous particulate matter, bacteria etc..

Epithelial cells secrete a layer of mucus, which traps

  • Sensory

    • Taste (Epithelium Taste Buds)

    • Touch, Temperature, Pain (Epithelium and laminate propia which have sensory receptors)

  • Synthesis/Secretion

    • Saliva (Minor salivary glands in lamina propia, submucosa)

    • Sebum (Sebaceous Glands in laminate propia)

What is the difference between orthokeratinised and parakeratinised epithelium?

Orthokeratinised - The cell nuclei disappears in the keratinised layer

Parakertainised - Nuclei remains int he keratinised layer

How is oral mucosa classified by function?

Functions:

  • Protection:

    • Mechanical role, preventing friction/abrasion (Epithelium), preventing compression/shearing (laminate propia which has collagen/elastin)

    • Barrier role against molecles and microorganisms (Epithelim)

  • Sensory

    • Taste (Epithelium Taste Buds)

    • Touch, Temperature, Pain (Epithelium and laminate propia which have sensory receptors)

  • Synthesis/Secretion

    • Saliva (Minor salivary glands in lamina propia, submucosa)

    • Sebum (Sebaceous Glands in laminate propia)

  • Esthetics

    • Vermilion Border of Lips