creamandcheese

Skin Care

In zootomy and dermatology, skin is an organ of the integumentary system made up of a layer of tissues that guard under the muscles and organs. As the interface between the surroundings it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation,sensation and vitamin D and B synthesis. Skin is considered one of the most important parts of the body.

Skin has pigmentation, provided by melanocytes, which absorbs some of the potentially dangerous radiation in sunlight. It also contains DNA repair enzymes which also cause UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has sometimes led to the classification of peoples on the basis of skin color.
Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly serves to augment the insulation the skin provides, but can also serve as a secondary sexual characteristics . On some animals the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier to pass the chemicals and is often subject to osmosis. A frog sitting in an anesthetic solution will quickly go to sleep.