ABSTRACT
Although encompassing a multitude of attributes, in its most widely appreciated context the skin barrier function refers to the epidermal barrier to water permeability. Indeed, this is one of the most crucial of integumentary functions that make terrestrial life possible. Large-scale damage to this barrier, as in third-degree burns, results in death by dehydration (due to unchecked water loss). An intact impermeable barrier allows the organism to soak in water without flooding its internal organs and keeps out many xenobiotics. The stratum corneum (SC), a tough, paper-thin superficial layer of skin, has evolved to meet this primary requirement. Compared to the rest of the skin, which weighs around 16% of the total body weight, the mass of SC is rather insignificant. However, its average surface area (1.6 to 1.9 m2 in an adult person) is a clear indication of its functional significance to the integumentary system. The skin serves as a primary defense, a sensory and an excretory organ, a key to temperature regulation, and a visual signal for intraspecific communication. Its barrier function extends to UV, oxidants, and immune barriers, as well as barriers in interracial relations that have shaped
human destiny. Functions and dysfunctions of skin affect not only the physical health, but also the self-esteem of the person. The latter aspect, once trivialized as vanity, is being increasingly recognized as important to emotional well being. This scientific attitude also has made the cosmetic and personal care industries focus on truly functional ingredients and products that perform, with an objective means of measuring the functional efficacy. As a result, research in skin biology has taken a truly interdisciplinary approach to encompass polymer sciences, measurement sciences (analytical), bio-and tissue-engineering and instrumentation, controlled-release and transdermal delivery of actives, in addition to the classic dermatological sciences, which have added molecular biology and genome sciences to its armamentarium of diagnosis and treatment.
