TY - CHAP M1 - Book, Section TI - Chapter 47. Skin as an Organ of Protection A1 - Proksch, Ehrhardt A1 - Jensen, Jens-Michael A2 - Goldsmith, Lowell A. A2 - Katz, Stephen I. A2 - Gilchrest, Barbara A. A2 - Paller, Amy S. A2 - Leffell, David J. A2 - Wolff, Klaus PY - 2012 T2 - Fitzpatrick's Dermatology in General Medicine, 8e AB - |PrintSkin Barrier at a GlanceThe most important function of the skin is to form a barrier between the organism and the environment.The skin barrier prevents excessive water loss (inside–outside barrier) and the entry of harmful substances from the environment (outside–inside barrier).The physical barrier is predominantly located in the stratum corneum.The stratum corneum barrier is composed of corneocytes and intercellular lipids, cholesterol, free fatty acids, and ceramides.Keratins and cornified envelope proteins are important for the mechanical stability of the corneocytes.The cornified envelope protein involucrin binds ceramides covalently, forming a backbone for the subsequent attachment of free ceramides.The nucleated epidermis through tight junctions and desmosomes also contributes to the barrier.Experimental barrier disruption increases epidermal lipids and changes in epidermal differentiation.The signals for barrier recovery are cytokines and the calcium ion gradient.Several diseases are characterized by a probably genetically disturbed barrier function. The disturbed barrier function contributes to disease pathology, in particular in contact dermatitis, atopic dermatitis, forms of ichthyosis, and psoriasis.Lipid or lipid-like creams and ointments can repair disturbed barrier function. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/29 UR - accessmedicine.mhmedical.com/content.aspx?aid=56034571 ER -