Editing Scar (section)

{{short description|Area of fibrous tissue that replaces normal skin after an injury}}
{{About|scar tissue<!--||Scar (disambiguation)|and|Scarred (disambiguation)|and|SCARS (disambiguation)-->}}
{{Use dmy dates|date=July 2014}}
{{Infobox medical condition (new)
| name            = Scar
| synonyms        = Cicatrix
| image           = File:Scar (xndr).jpg
| caption         = Scar tissue on an arm
| field           = [[Dermatology]], [[plastic surgery]]
}}
A '''scar''' (or '''scar tissue''') is an area of [[fibrosis|fibrous tissue]] that replaces normal [[skin]] after an [[injury]]. Scars result from the biological process of [[wound repair]] in the skin, as well as in other [[Organ (anatomy)|organ]]s, and [[biological tissue|tissues]] of the body. Thus, scarring is a natural part of the [[healing]] process. With the exception of very minor [[lesion]]s, every wound (e.g., after [[accident]], [[disease]], or [[surgery]]) results in some degree of scarring. An exception to this are animals with complete [[Regeneration (biology)|regeneration]], which regrow tissue without scar formation.

Scar tissue is composed of the same protein ([[collagen]]) as the tissue that it replaces, but the fiber composition of the protein is different; instead of a random basketweave formation of the collagen fibers found in normal tissue, in [[fibrosis]] the collagen cross-links and forms a pronounced alignment in a single direction.<ref name="collagenskinscar2010-08-20">{{Cite web  | last = Sherratt  | first = Jonathan A.  | title = Mathematical Modelling of Scar Tissue Formation  | quote = This is composed of the same main protein (collagen) as normal skin, but with differences in details of composition. Most crucially, the protein fibres in normal tissue have a random (basketweave) appearance, while those in scar tissue have pronounced alignment in a single direction.  | publisher = Department of Mathematics, Heriot-Watt University  | year = 2010  | url = http://www.ma.hw.ac.uk/~jas/researchinterests/scartissueformation.html  | access-date = 20 August 2010}}</ref> This collagen scar tissue alignment is usually of inferior functional quality to the normal collagen randomised alignment. For example, scars in the skin are less resistant to [[ultraviolet radiation]], and [[sweat gland]]s and [[hair follicle]]s do not grow back within scar tissues.<ref name=Kraftlynde/> A [[myocardial infarction]], commonly known as a heart attack,  causes [[Myocardial scarring|scar formation]] in the [[heart]] muscle, which leads to loss of muscular power and possibly [[heart failure]]. However, there are some tissues (e.g. [[bone]]) that can heal without any structural or functional deterioration.
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