Oral Mucosa Development and Functions
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Questions and Answers

What is the primary role of the oral mucosa in relation to microorganisms?

  • Facilitate taste sensation
  • Secretion of digestive enzymes
  • Barrier and immunological defense (correct)
  • Enhance thermal regulation

    • Which statement best describes the origin of the palatal and gingival epithelium?

  • Neuroectodermal origin
  • Derived from mesoderm
  • Ectodermal origin (correct)
  • Endodermal origin

    • Which of the following is NOT a function of the oral mucosa?

  • Secretion
  • Sensation
  • Photosynthesis (correct)
  • Thermal regulation

    • During which day of gestation does the primitive oral cavity begin to form?

    <p>26 days</p> Signup and view all the answers

    Which type of receptors in the oral mucosa are involved in reflex actions like swallowing?

    <p>Mechanoreceptors</p> Signup and view all the answers

    What component of saliva is essential for maintaining moist surfaces in the oral cavity?

    <p>Buffering agents</p> Signup and view all the answers

    Which of the following types of epithelium is found in different regions of the oral cavity?

    <p>Stratified squamous epithelium</p> Signup and view all the answers

    Which cellular component provides a barrier against abrasions in the oral mucosa?

    <p>Keratinocytes</p> Signup and view all the answers

    What differentiates masticatory mucosa from lining mucosa?

    <p>Masticatory mucosa is keratinised and withstands friction.</p> Signup and view all the answers

    Which statement is true regarding Fordyce granules?

    <p>They appear as yellowish-white papular lesions.</p> Signup and view all the answers

    Which type of mucosa is most abundant in the oral cavity?

    <p>Lining mucosa</p> Signup and view all the answers

    What is a major characteristic of non-keratinised mucosa?

    <p>It is mobile and distensible.</p> Signup and view all the answers

    Which of the following structures is NOT an appendage found in mucosa?

    <p>Hair follicles</p> Signup and view all the answers

    Which area of the oral cavity does the lining mucosa NOT cover?

    <p>Dorsum of the tongue</p> Signup and view all the answers

    What is the primary role of minor salivary glands in the submucosa?

    <p>Act as a barrier to pathogens.</p> Signup and view all the answers

    What distinguishes the lining mucosa from masticatory mucosa?

    <p>Lining mucosa is less resilient to compression.</p> Signup and view all the answers

    What component separates the epithelium from the underlying connective tissue in the oral mucosa?

    <p>Basement membrane</p> Signup and view all the answers

    Which layer of the lamina propria is located between the rete ridges?

    <p>Papillary LP</p> Signup and view all the answers

    Which cells are NOT typically found in the lamina propria?

    <p>Chondrocytes</p> Signup and view all the answers

    What is necessary for the metabolic needs of the avascular epithelium when the submucosa is absent?

    <p>Secondary plexus</p> Signup and view all the answers

    Which type of collagen is NOT found within the fibers of the lamina propria?

    <p>Type II</p> Signup and view all the answers

    Which structure is primarily associated with supporting the epithelium in the oral mucosa?

    <p>Lamina propria</p> Signup and view all the answers

    Which type of mucosa is characterized as keratinised and masticatory?

    <p>Gingiva</p> Signup and view all the answers

    Which of the following components is NOT part of the ground substance in the lamina propria?

    <p>Neural elements</p> Signup and view all the answers

    Which type of mucosa is mostly absent of sensory function?

    <p>Lining mucosa</p> Signup and view all the answers

    What is the primary cellular composition of the transient inflammatory cells found in the oral mucosa?

    <p>Lymphocytes</p> Signup and view all the answers

    Among the following, which layer is directly above the lamina propria in oral mucosa?

    <p>Epithelium</p> Signup and view all the answers

    What component is especially prominent in the masticatory mucosa compared to lining mucosa?

    <p>Rete ridges</p> Signup and view all the answers

    Which structure serves as an interface between the epithelium and the connective tissue in oral mucosa?

    <p>Basement membrane</p> Signup and view all the answers

    What type of collagen primarily constitutes the lamina densa?

    <p>Type IV collagen</p> Signup and view all the answers

    What does the lamina lucida primarily consist of?

    <p>Glycoproteins</p> Signup and view all the answers

    What autoimmune condition could involve antibodies targeting the components of the mucosal desmosomes?

    <p>Pemphigus vulgaris</p> Signup and view all the answers

    Which component of the connective tissue is primarily responsible for the structural integrity of the lamina propria?

    <p>Fibroblasts</p> Signup and view all the answers

    Which statement accurately describes the rete ridges in the masticatory mucosa?

    <p>They facilitate metabolic exchange.</p> Signup and view all the answers

    What characterizes the vermilion zone of the lip?

    <p>Requires constant moistening with saliva</p> Signup and view all the answers

    Which epithelium type has the fastest turnover rate?

    <p>Junctional epithelium</p> Signup and view all the answers

    What changes occur in the oral mucosa with age?

    <p>Smoother and dryer mucosal surface</p> Signup and view all the answers

    Which statement accurately reflects the condition of sebaceous glands in the elderly?

    <p>They show signs of atrophy</p> Signup and view all the answers

    What is the function of the intermediate zone in infants?

    <p>To form suckling pads</p> Signup and view all the answers

    How is the cell-mediated immunity affected with age?

    <p>It declines over time</p> Signup and view all the answers

    What describes the connective tissue changes observed in the elderly oral mucosa?

    <p>Flattening of epithelial ridges</p> Signup and view all the answers

    What notable feature is seen in the dorsum of the tongue with age?

    <p>Glossy appearance with more prominent fungiform papillae</p> Signup and view all the answers

    Study Notes

    Oral Mucosa

    • Moist lining of the GI tract, nasal passages and other body cavities communicating with the external environment.
    • Continuous with the skin (lips area) and with the rest of the gut (pharynx).
    • Located between the skin and gastrointestinal (GI) tract.
    • Shares similar components with skin and GI lining: a covering epithelium and underlying connective tissue.

    Development of Oral Mucosa

    • Primitive oral cavity (stomodeum) fuses to foregut after the rupture of the buccopharyngeal membrane (26 days of gestation).
    • Structures that develop from branchial arches (tongue, epiglottis, pharynx) are covered by epithelium derived from endoderm.
    • Palatal, buccal, gingival epithelium and epithelium covering the floor of the mouth and lips are ectodermal origin.

    Functions of Oral Mucosa

    • Protection:
      • Withstand compression, stretching, shearing, abrasion & bacterial influences.
      • Barrier to microorganisms, toxins and various antigens.
      • Immunological defense mechanisms: humoral and cell mediated.
    • Sensation:
      • Temperature, pressure, pain, taste.
      • Reflex receptors for swallowing, gagging.
    • Secretion:
      • Maintenance of moist surface, buffering, secretion of antibodies.
      • Major salivary glands produce saliva.
      • Minor salivary glands are present in the submucosa except gingiva and anterior part of the hard palate.
    • Thermal regulation:
      • In animals like dogs, panting helps regulate body temperature.

    Differences Between Oral Mucosa and Skin

    • Oral mucosa:
      • Absence of skin appendages but has salivary glands.
      • Sometimes ectopic sebaceous glands (Fordyce’s granules).
      • Smoother with less wrinkles.
      • Deeply colored.
    • Skin:
      • Hair follicles, sebaceous glands, sweat glands.

    Fordyce Granules

    • Common soft tissue variation seen in the oral cavity.
    • Ectopic sebaceous glands.
    • Characterized by yellowish-white papular lesions scattered throughout the oral mucous membrane.
    • More common in the buccal mucosa.

    Similarities Between Oral Mucosa and Skin

    • Both have:
      • Covering epithelium
      • Underlying connective tissue

    Organization of Oral Cavity

    • Outer vestibule:
      • Bounded by lips & cheeks.
    • Oral cavity proper:
      • Separated from vestibule by alveolus bearing teeth and gingiva.
      • Superior: Hard and soft palate.
      • Inferior: Floor of mouth & tongue base.
      • Posterior: Fauces & tonsils.

    Regional Variation of Oral Mucosa

    • Lining mucosa (60%):
      • Mobile and distensible.
      • Non-keratinized mucosa.
      • Found in the whole mouth except gingiva, hard palate, and dorsum of the tongue.
    • Masticatory mucosa (25%):
      • Attached to bone (muco-periosteum).
      • Resists high levels of friction & compression.
      • Keratinized type of mucosa.
      • Found in gingiva, hard palate, and dorsum of the tongue.
    • Specialized mucosa (15%):
      • Found in the dorsal surface of the tongue.

    Lining Mucosa

    • Composed of non-keratinized stratified squamous epithelium.
    • Found in areas of the oral cavity where there is less wear and tear.
    • Thinner and more flexible than masticatory mucosa.

    Masticatory Mucosa

    • Composed of keratinized stratified squamous epithelium.
    • Found in areas of the oral cavity that are subject to more wear and tear, such as the hard palate and gingiva.
    • Provides a protective barrier against abrasion and injury.

    Composition of Oral Mucosa

    • Overlying epithelium:
      • Epidermis in skin.
    • Basement membrane:
      • Between epithelium & lamina propria.
    • Underlying connective tissue (lamina propria):
      • Dermis in skin.
      • Supports and nourishes the epithelium.

    Epithelium-Connective Tissue Interface

    • Epithelium projections into underlying connective tissue: rete ridges.
    • Larger interface with stronger binding.
    • Interface for metabolic exchange (epithelium has no blood vessels).
    • More numerous, longer, and thinner in masticatory mucosa than lining mucosa.

    Basement Membrane

    • Composed of two zones:
      • Lamina lucida: immediately underneath the epithelium.
      • Lamina densa: finely granular or filamentous material of type IV collagen.

    Clinical Considerations

    • Auto-immune diseases: antibodies directed against any element of the desmosomes, hemidesmosomes, basement membrane.
    • Split between epithelium & underlying connective tissue - sloughing of epithelium.

    Lamina Propria

    • Connective tissue supporting the epithelium.
    • Two layers:
      • Papillary LP between rete ridges.
      • Reticular (net-like) LP.
    • Cells: fibroblasts, macrophages, mast cells, inflammatory cells.
    • Fibers: collagen (type I & III, IV & VII in basal lamina), elastic fibres.
    • Ground substance.

    Vascular Supply of Mucosa

    • Deep plexus of vessels in submucosa or deep reticular layer.
    • Secondary plexus in LP when submucosa is absent.
    • Necessary for metabolic needs of the avascular epithelium.

    Regional Variations in Mucosal Structure

    • Non-keratinized/ Lining/ Alveolar Mucosa:
      • Labial mucosa inside lips.
      • Cheek.
      • Soft palate.
      • Floor of mouth and ventral surface of the tongue.
    • Keratinized/ Masticatory Mucosa:
      • Hard palate.
      • Gingiva.
      • Dorsum of the tongue.

    Vermilion Zone

    • Lacks appendages of skin.
    • Sebaceous glands at the angles of the mouth.
    • Lacks mucous glands, needs constant moistening with saliva.
    • Keratinized translucent epithelium.
    • Long and narrow connective tissue papillae with capillary loops.
    • Junction between vermillion zone and labial mucosa is INTERMEDIATE ZONE - no granular layer, thick parakeratinised layer.
    • Forms suckling pads in infants.

    Turnover Times of Oral Epithelium

    • Skin: 52-75 days.
    • Gingiva: 41-57 days.
    • Cheek: 25 days.
    • Junctional epithelium: 5-6 days.
    • Non-keratinized epithelium turns over faster than keratinized epithelium.

    Age Changes of Oral Mucosa

    • Mucosal surface is smoother, dryer, atrophic, and friable due to cumulative effect of systemic diseases and medication.
    • Histologically: epithelium is thinner, smooth epithelium-connective tissue interface, flattening of epithelial ridges, lamina propria shows decreased cellularity and increased amount of cross-linked collagen.
    • Dorsum of the tongue: glossy appearance, reduced number of filiform papillae, more prominent fungiform papillae.
    • Declined cell-mediated immunity.
    • Development of varicosities.
    • Sebaceous glands of the lips and cheeks are more prominent, minor salivary glands show atrophic signs.
    • Dryness of mouth, burning sensation, abnormal taste.

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    Description

    This quiz explores the structure, development, and essential functions of the oral mucosa, including its role as a barrier and its developmental origins. Delve into the protective mechanisms and the evolution of this critical lining in the gastrointestinal tract.

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