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The structure of the skin


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Epidermis
Dermis
Subcutaneous fat
Blood and lymphatic vessels
Hair follicle
Sweat glands
Nerves

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       Keratinocyte and keratinization
Horny layer
Granular layer- keratinohyaline granules
Stratum spinosum
Basal cell layer

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Horny layer  - epidermal barrier


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Epidermal melanin unit  1/36
Tyrosine – Dopa – Dopaquinone – Eumelanin, phaeomelanin
Tyrosinase

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Dermo epidermal junction -basement membrane zone


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Dermis – fibres, ground substance , cells


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Pilosebaceous unit
Hair cycle anagen – katagen – telogen             1000 – 10 – 100 days

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Nerves
Nerve endings
Merkel cells
Corpuscles
Itch

The function of the skin
§1. Protection against
§chemicals
§physical factors – UV, cold, heat
§Infections
§antigens
§
§Horny layer
§Melanocytes
§Langerhans cells
§

The function of the skin
§2.Preservation of balanced internal environment
§Loss of water, electrolytes, macromolecules
§3. Temperature regulation
§
§4. Shock absorber
§
§5. Sensation
§
§6. Energy reserve
§
§7. Vitamin D synthesis
§Horny layer
§
§
§
§Blood vessels, eccrine sweat glands
§Dermis, subcutaneous fat
§
§Nerves
§
§Subcutaneous fat
§
§Keratinocytes

The function of the skin
§8.Protection and fight
§
§9. Psychosocial function
§
§10. Body odour
§Nails, hair
§
§Cosmetic quality, lips, hair
§
§Apocrine sweat glands

Some functions of dermal resident cells
§Fibroblast   synthesis of collagen, reticulin, elastin, fibronectin, glycosaminoglycans
§
§Mononuclear phagocyte phagocytose (bacteria), cytokine secretion
§Lymphocyte – immunosurveillance
§Mast cell – release of mediators (histamine, heparin, prostagalndins, leukotirens, tryptase etc