Last updated: 2020-02-11 | 2987 Views |
The epidermis of skin and the oral mucosa are highly specialized stratified epithelia that function to protect the body from physical and chemical damage, infection, dehydration, and heat loss. To maintain this critical barrier, epithelial tissues undergo constant renewal and repair. Epithelial cells (keratinocytes) undergo a program of terminal differentiation, expressing a set of structural proteins, keratins, which assemble into filaments and function to maintain cell and tissue integrity. Two types of cell adhesion structures, desmosomes and hemidesmosomes, function to glue keratinocytes to one another and to the basement membrane, and connect the keratin cytoskeleton to the cell surface. Keratinizing epithelia such as the epidermis and oral gingiva that have to withstand severe physical and chemical forces produce a toughened structure, the cornified cell envelope. This envelope is a major component of the epithelial barrier at the tissue surface.
Epithelial tissues provide a barrier between an organism and its environment and perform many additional specialized functions depending on body site. In order to function correctly, stratified epithelia such as the epidermis and oral mucosa have to maintain tight cell-cell adhesion in the living cells and retain the dead, keratinized squames as a protective sheath prior to being sloughed. This barrier provides protection from mechanical and chemical stresses as well as being a selective permeability barrier. The importance of both cell adhesion junctions and the cornified envelope in maintaining cell and tissue integrity and preventing dessication is demonstrated by the large number of
genetic and autoimmune diseases that result from altered expression or function of these structures.
Function of oral mucosa
The oral mucosa has several functions. Its main purpose is to act as a barrier. It protects the deeper tissues such as fat, muscle, nerve and blood supplies from mechanical insults, such as trauma during chewing, and also prevents the entry of bacteria and some toxic substances into the body.
The oral mucosa has an extensive innervation of nerves, which allows the mouth to be very receptive of hot and cold, as well as touch. Taste buds are also located in oral mucosa and are important for recognition of taste.
The major secretion associated with the oral mucosa is saliva, produced by the salivary glands. The major salivary glands secrete most of the saliva via ducts that pass through the oral mucosa.
There is a degree of permeability that allows for rapid absorption into the body in certain circumstances e.g. the permeability of the oral mucosa is utilised in the rubbing of orange juice, or another sugary drink when diabetics suffer from a low-blood sugar.
Recent findings have led to the realization that these barriers are not only physical, they also generate potent antimicrobial peptides ( Innate Immunity ). Disruption of this barrier leads to bacterial invasion and subsequent inflammation. This is precisely the situation existing in the human oral cavity, where tissues are constantly exposed to a variety of microbial challenges that can lead to bacterially induced periodontal diseases, and to infections of the oral mucosa by bacteria, fungi, and viruses. It is theorized that epithelial cell-derived antimicrobial peptides function to keep the natural flora of micro-organisms in a steady state in different niches such as the skin, the intestines, the airway, the endocervix, and the mouth.
Ref: - https://www.myvmc.com/anatomy/oral-mucosa/
Making Sense of the Epithelial Barrier: What Molecular Biology and Genetics Tell Us About the Functions of Oral Mucosal and Epidermal Tissues
Richard B. Presland, Ph.D.; Richard J. Jurevic, D.D.S.
- Molecular Approaches to Oral Therapeutics: Dentistry in the Next Millennium?
Michael L. Barnett
- EPITHELIAL ANTIMICROBIAL PEPTIDES: REVIEW AND SIGNIFICANCE FOR ORAL APPLICATIONS
Department of Periodontics, (ase Western Reserve University, 10900 Euclid Ave., Cleveland, Ohio 44106-4905; and Department of Oral Biology, Box 357444, University of Washington, Seattle, Washington 98195-7444