functions of Skin

-by liberating sweat at its surface and by adjusting the flow of blood in the dermis help regulate body temerature.

• -Keratin protects underlying tissue from microbes, abrasion, heat and chemicals and the tightly interlocked keratinocytes resist invasion by microbes
• -Lipids released by lamellar granules inhibit evaporation of water
• -sebum keeps skin and hair from drying out and containt a bactericidal chemical to kill surface bacteria
• -melanin helps protect from uv rays
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• are sensations that arise in the skin; including tactile sensations as well as thermal sensation such as warmth and coolness, and pain
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the elimination of substances from the body and the passage of materials from the external environment into the body cells.

• -requires acitvation of a precursor molecule in the skin by uv rays in sunlight
• -enzymes in the liver and kidneys then modify the activated molecule, finally producing calcitriol, which is the most active form of vitamin D.  

• -the central part of the wound usually extends down to the dermis; the wound edges invovle only superficial damage to the epidermal cells
• -they are repaired by the enlargement and migration of basal cells, contact inhibition, and the division of migratory and stationary basal cells

a blod clot unites the wound edges, epithial cells migrate across the wound, vasodilation and increased permiability of blood vessels enhance delivery of phagocytes and mesenchymal cells develop into fibroblasts.

Fibroblasts migrate along fibrin threads and begin synthesizing collagen fibres and glycoproteins

epithelial cells grow extensively

the scab sloughs off, the epidermis is restored to normal thickness, collagen fibers become more organized, fibroblasts begin to disappear, and blood vessels are restored to normal

• most common is Basal cell carcinomas
• -caused by excessive exposure to the sun
• risk factors: skin type, age, sun exposure, family history, immunological status 

is tissue damage caused by  excessive heat, electricity, radioactivity, or corrosive chemicals that denature the proteins in the skin cells

- First degree burns- involves only epidermis = mild pain and redness but no blisters

-Second degree burns- destroy the epidermis and part of the dermis = redness, blister formation, edema and pain 

-Third degree burns- destroys the Epidermis, dermis and Subcutaneous layer. Most skin functions are lost (loss of sensitivity to pain entirely)  

A lesion, usually in oral mucous membrane, caused by Type 1 herpes simplex virus transmitted by oral or respritory routes.

An inflammation of the skin caused by characterized by patches of red, blistering, dry extremely itchy skin. It typically begins in infancy and most children out grow it. 

reddened elevated patches of skin that are often itchy.  Msot commonly caused by infections, physical trauma, medications, emotional stress, food additives and allergies.

Mass produced by uncontrolled growth of epithelial skin cells; caused by a papillomavirus.  Most warts are none cancerous.