ABSTRACT
The skin forms the body’s defensive perimeter against what is in reality the biologically hostile environment we humans live in. As such, in the normal course of living, it suffers more physical and chemical insult than any other tissue of the body. It is inadvertently scraped, abraded, scratched, bruised, cut, nicked, and burned. Insects bite it, sting it, and occasionally furrow through it. It is exposed to detergents, solvents, and myriad other chemicals and residues. Bacteria, yeasts, molds, and fungi live on its surface and within its cracks and crevices. It is brushed, smeared, dusted, sprayed, and otherwise anointed with toiletries, cosmetics, and drugs. Any of these exposures can rile the skin and/or provoke allergy. If there is only minor damage associated with such insults, the skin repairs itself in short order without a trace left of the injury. If the insult is severe, its reconstruction takes far longer and may occur with scarring. Such repair is essential in that humans cannot survive for long with an extensively damaged skin because it is the skin that keeps us from losing water and life’s other essential chemicals to the external environment. In its intact state the skin is a formidable barrier, resistant to chemicals and tissue-harmful ultraviolet rays and virtually impenetrable to life-threatening microorganisms. To perform these necessary functions, the skin has to be tough and at the same time flexible, for it is stretched and flexed continually as we move around within it. In its healthy state it is thus a remarkable fabric, strong and far more complex than any man-made material [1].
