The Epidermis Essay

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The epidermis The epidermis is the topmost layer of the skin. It is the first barrier between you and the outside world. The epidermis consists of three types of cells keratinocytes, melanocytes and Langerhans cells. Keratinocytes, the cells that make the protein keratin, are the predominant type of cells in the epidermis. The total thickness of the epidermis is usually about 0.5 - 1 mm. At the lowermost portion of the epidermis are immature, rapidly dividing keratinocytes. As they mature, keratinocytes lose water, flatten out and move upward. Eventually, at the end of their life cylce, they reach the uppermost layer of the epidermis called stratum corneum. Stratum corneum consists mainly of dead keratinocytes, hardened proteins (keratin) and lipids, forming a protective crust. Dead cells from stratum corneum continuously slough off and are replaced by new ones coming from below. The skin completely renews itself every 3 - 5 weeks. Most mild peels work by partly removing the stratum corneum and thus speeding up skin renewal. Another significant group of cell in the epidermis are melanocytes, the cells producing melanin, the pigment responsible for skin tone and color. Finally, Langerhans cells are essentially a forepost of the immune system in the epidermis. They prevent unwanted foreign substances from penetrating the skin. The condition of epidermis determines how "fresh" your skin looks and also how well your skin absorbs and holds moisture. Wrinkles, however, are formed in lower layers. The dermis The dermis is the middle layer of the skin located between the epidermis and subcutaneous tissue. It is the thickest of the skin layers and comprises a tight, sturdy mesh of collagen and elastin fibers. Both collagen and elastin are critically important skin proteins: collagen is responsible for the structural support and elastin for the resilience of the skin. The key

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