Editing Fatty acid (section)

==Skin==
The [[stratum corneum]] {{ndash}} the outermost layer of the [[epidermis]] {{ndash}} is composed of terminally [[Cellular differentiation|differentiated]] and [[Enucleation (microbiology)|enucleated]] [[corneocyte]]s within a lipid matrix.<ref name=":0">{{cite journal | last1=Knox | first1=Sophie | last2=O'Boyle | first2=Niamh M. | title=Skin lipids in health and disease: A review | journal=Chemistry and Physics of Lipids | volume=236 | year=2021 | issn=0009-3084 | pmid=33561467 | doi=10.1016/j.chemphyslip.2021.105055 | page=105055| s2cid=231864420 | doi-access=free }}</ref> Together with [[cholesterol]] and [[ceramide]]s, free fatty acids form a water-impermeable barrier that prevents [[evaporation|evaporative water loss]].<ref name=":0"/> Generally, the epidermal lipid matrix is composed of an equimolar mixture of ceramides (about 50% by weight), cholesterol (25%), and free fatty acids (15%).<ref name=":0"/> Saturated fatty acids 16 and 18 carbons in length are the dominant types in the epidermis,<ref name=":0"/><ref name=":1">{{Cite journal|display-authors=3 |last1=Merleev |first1=Alexander A. |last2=Le |first2=Stephanie T. |last3=Alexanian |first3=Claire |last4=Toussi |first4=Atrin |last5=Xie |first5=Yixuan |last6=Marusina |first6=Alina I. |last7=Watkins |first7=Steven M. |last8=Patel |first8=Forum |last9=Billi |first9=Allison C. |last10=Wiedemann |first10=Julie |last11=Izumiya |first11=Yoshihiro |last12=Kumar |first12=Ashish |last13=Uppala |first13=Ranjitha |last14=Kahlenberg |first14=J. Michelle |last15=Liu |first15=Fu-Tong |date=2022-08-22 |title=Biogeographic and disease-specific alterations in epidermal lipid composition and single-cell analysis of acral keratinocytes |journal=JCI Insight |volume=7 |issue=16 |pages=e159762 |doi=10.1172/jci.insight.159762 |issn=2379-3708 |pmc=9462509 |pmid=35900871}}</ref> while unsaturated fatty acids and saturated fatty acids of various other lengths are also present.<ref name=":0"/><ref name=":1" /> The relative abundance of the different fatty acids in the epidermis is dependent on the body site the skin is covering.<ref name=":1" /> There are also characteristic epidermal fatty acid alterations that occur in [[psoriasis]], [[atopic dermatitis]], and other [[inflammation|inflammatory conditions]].<ref name=":0"/><ref name=":1" />