Editing Extracellular fluid (section)

{{short description|Body fluid outside the cells of a multicellular organism}}
[[File:Cellular Fluid Content.jpg|thumb|250 px|The distribution of the [[Body water|total body water]] in [[mammals]] between the [[intracellular fluid|intracellular compartment]] and the extracellular compartment, which is, in turn, subdivided into [[interstitium|interstitial]] fluid and smaller components, such as the [[blood plasma]], the [[cerebrospinal fluid]] and [[lymph]]]]

In [[cell biology]], '''extracellular fluid''' ('''ECF''') denotes all [[body fluid]] outside the [[Cell (biology)|cells]] of any [[multicellular organism]]. [[Body water|Total body water]] in healthy adults is about 50&ndash;60% (range 45 to 75%) of total body weight;<ref>{{Cite journal |last1=Chumlea |first1=W. Cameron |last2=Guo |first2=Shumei S. |last3=Zeller |first3=Christine M. |last4=Reo |first4=Nicholas V. |last5=Siervogel |first5=Roger M. |date=1999-07-01 |title=Total body water data for white adults 18 to 64 years of age: The Fels Longitudinal Study |journal=Kidney International |volume=56 |issue=1 |pages=244–252 |doi=10.1046/j.1523-1755.1999.00532.x |pmid=10411699 |issn=0085-2538|doi-access=free }}</ref> women and the obese typically have a lower percentage than lean men.<ref name=":1">{{Cite web|url=http://www.anaesthesiamcq.com/FluidBook/fl2_1.php|title=Fluid Physiology: 2.1 Fluid Compartments|website=www.anaesthesiamcq.com|access-date=2019-11-28}}</ref> Extracellular fluid makes up about one-third of body fluid, the remaining two-thirds is [[intracellular fluid]] within cells.<ref>{{cite book| vauthors = Tortora G |title=Principles of anatomy and physiology| url = https://archive.org/details/principlesofan1987tort | url-access = registration |date=1987|publisher=Harper and Row|location=New York|isbn=978-0-06-350729-6|page=[https://archive.org/details/principlesofan1987tort/page/693 693]|edition=5th}}</ref> The main component of the extracellular fluid is the [[#Interstitial fluid|interstitial fluid]] that surrounds cells. 

Extracellular fluid is the internal environment of all [[multicellular organism|multicellular animals]], and in those animals with a [[blood]] [[circulatory system]], a proportion of this fluid is [[blood plasma]].<ref>{{cite book|last1=Hillis|first1=David | name-list-style = vanc |title=Principles of life|date=2012|publisher=Sinauer Associates|location=Sunderland, MA|isbn=978-1-4292-5721-3|page=589}}</ref> Plasma and interstitial fluid are the two components that make up at least 97% of the ECF. [[Lymph]] makes up a small percentage of the interstitial fluid.<ref>{{cite book|last1=Pocock|first1=Gillian|last2=Richards|first2=Christopher D. | name-list-style = vanc |title=Human physiology : the basis of medicine|date=2006|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-856878-0|page=548|edition=3rd}}</ref> The remaining small portion of the ECF includes the [[transcellular fluid]] (about 2.5%). The ECF can also be seen as having two components – plasma and lymph as a delivery system, and interstitial fluid for water and solute exchange with the cells.<ref name="pmid_19817339">{{cite journal | vauthors = Canavan A, Arant BS | title = Diagnosis and management of dehydration in children | journal = American Family Physician | volume = 80 | issue = 7 | pages = 692–696 | date = October 2009 | pmid = 19817339 | url = http://www.aafp.org/afp/2009/1001/p692.pdf }}</ref>

The extracellular fluid, in particular the interstitial fluid, constitutes the body's [[milieu intérieur|internal environment]] that bathes all of the [[Cell (biology)|cells]] in the body. The ECF composition is therefore crucial for their normal functions, and is maintained by a number of [[Homeostasis|homeostatic mechanisms]] involving [[negative feedback]]. Homeostasis regulates, among others, the [[pH#Living systems|pH]], [[sodium]], [[potassium]], and [[calcium]] concentrations in the ECF. The volume of body fluid, [[blood glucose]], [[oxygen]], and [[carbon dioxide]] levels are also tightly homeostatically maintained.

The volume of extracellular fluid in a young adult male of 70&nbsp;kg (154 lbs) is 20% of body weight – about fourteen liters. Eleven liters are interstitial fluid and the remaining three liters are plasma.<ref name="Hall">{{cite book|last1=Hall|first1=John| name-list-style = vanc |title=Guyton and Hall textbook of medical physiology|date=2011|publisher=Saunders/Elsevier|location=Philadelphia|isbn=978-1-4160-4574-8|pages=286–287|edition=12th}}</ref>