Epidermal Cell Types
There are four main types of cells within the epidermis; some found in only one layer, others found in more than one layer. Keratinocytes are the predominant cell type, constituting 95% of epithelial cells. They produce the keratin and are found throughout the epidermis. Those keratinocytes in the deepest layer are also known as basal cells. The primary function of this cell type is the formation of the keratin layer, which prevents excessive water loss and protects the skin and underlying tissue from chemical and pathogenic invasion, making the skin a natural barrier to infection. It also plays another role in the immune system by inhibiting or stimulating inflammation, based on the presence or absence of provoking factors. Keratinocytes that form the outermost layer are constantly shed and replaced by new cells. The average lifespan of a keratinocyte is approximately 28 to 48 days from differentiation to exfoliation.
Q: [Underlying tissue] - Tissue that lies beneath the surface of the skin such as fatty tissue,
supporting structures, muscle, and bone.
Q: [Differentiation] - The process by which a less specialized cell becomes a more specialized cell type
Q: [Exfoliation] - The removal of the oldest dead skin cells on the skin's outermost surface
Q: [Infection] - Invasion of the body by living microorganisms
Q: [Inflammation] - A response of body tissues to injury or irritation characterized by pain, swelling, redness and heat.