ANTC62H3 Chapter : article 6.doc
Document Summary
Dark skin evolved pari passu with the loss of body hair and was the original state for the genus homo+ The largest and most massive of the organs of the body, the skin of the average adult human exceeds 2 m2 yet is generally no thicker than 2 mm. Lacking adequate protection from hair, human skin has undergone numerous adaptive structural changes that give it strength, resilience, and sensitivity. The skin of humans, like that of all tetrapods, acts as a sun shield to protect the body from most solar uv radiation (uvr) and is the locus for the initiation of the important, Uvr-driven process of vitamin d production in the body. Epidermis a thinner outer layer, the epidermis, and a thicker and more internally complex inner layer, the dermis. The skin"s elasticity and resistance to physical and chemical attack can be attributed to the high elastic modulus and unique amino acid composition of the keratinized layer of the epidermis.
