The epidermis is the thin, outer layer the the skin that is clearly shows to the eye and works to provide protection because that the body. This component of the skin does not contain any type of blood vessels and is, therefore, dependent on the dermis, i beg your pardon is the layer of the skin located straight underneath the epidermis, come provide access to nutrients and also dispose the waste.
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Keratinocytes
Keratinocytes room the most common type of cabinet in the epidermis and are responsible for the synthetic of the protein keratin. This cells exist in progressive stages of differentiation from the deepest to the superficial layers of cells.
Moreover, keratinocytes originate from the basal layer, i m sorry is the deepest layer of the epidermis, and gradually move up come the external layer that the epidermis. Here, keratinocytes are shed from the skin and replaced by new maturing cells.
Melanocytes
Melanocytes space another form of cell in the epidermis the are current throughout the basal layer. These cells room responsible for the manufacturing of melanin, i m sorry contributes to the shade of the skin the the individual. Melanin likewise helps to protect the body from ultraviolet (UV) radiation existing in sunshine that can damages the DNA of the skin cells.
Langerhans cells
Langerhans cells produced in the bone marrow are additionally present in the epidermis and also work come detect foreign substances and also infections as part of the immune system of the skin. These cells are likewise thought to be involved in the breakthrough of skin allergies.
Merkel cells
Merkel cell originate indigenous neural comb cells and are responsible for the late of gentle touch. These cells are existing in the epidermis in certain areas of the skin, such together the pond beds and genitalia.
Structure
The epidermis is composed of stratified squamous epithelial cells. There are 4 layers that the epidermis, according to the maturation of the cells:
Stratum germinativumStratum spinosumStratum granulosumStratum corneum
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The stratum germinativum is the innermost layer, i beg your pardon adjoins the dermal layer of skin, and also where the keratinocyte cells originate. Comparatively, the stratum corneum is the outermost layer, i beg your pardon is reasonably waterproof and also prevents the entrance of bacteria, viruses, and also other international substances into the body.
The thickness of the epidermis depends on the level of protection required for that area of the body. For example, the palms that the hands and also the soles that the feet have actually a significantly thicker class of keratin in the epidermis that deserve to have a thickness of approximately 2.3 millimeters (mm). This protects the human body from the high impact to i m sorry these locations of the body are subject. In contrast, the thickness of the epidermis on the eyelids is around 0.05 mm thick.
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Function
All great of the skin, including the epidermis, are responsible for the defense of the body, consisting of internal organs, muscles, nerves, and blood vessels. Added roles the the epidermis include:
Production of brand-new skin cellsProduction that melanin to give shade to the skin, and reduce the absorption and affect of UV radiationPhysical security of the bodyImmune protection of the bodyDependence top top the dermis
As there is no straight blood it is provided to the epidermis, this outermost layer of the skin depends on the underlying dermis, because that the supply of nutrients and also disposal of waste products. This occurs via a process of diffusion through the dermo-epidermal junction, i beg your pardon lies just listed below the stratum germinativum that the epidermis.