Editing Factor VII (section)

== Physiology ==

The main role of factor VII (FVII) is to initiate the process of coagulation in conjunction with [[tissue factor]] (TF/factor III). Tissue factor is found on the outside of blood vessels - normally not exposed to the bloodstream. Upon vessel injury, tissue factor is exposed to the blood and circulating factor VII. Once bound to TF, FVII is activated to FVIIa by different proteases, among which are [[thrombin]] (factor IIa), factor Xa, IXa, XIIa, and the FVIIa-TF complex itself. The complex of factor VIIa with TF catalyzes the conversion of factor IX and factor X into the active proteases, factor IXa and factor Xa, respectively.<ref>{{cite journal | vauthors = Wajima T, Isbister GK, Duffull SB | title = A comprehensive model for the humoral coagulation network in humans | journal = Clinical Pharmacology and Therapeutics | volume = 86 | issue = 3 | pages = 290–298 | date = September 2009 | pmid = 19516255 | doi = 10.1038/clpt.2009.87 | s2cid = 205121835 }}</ref>

The action of the factor is impeded by [[tissue factor pathway inhibitor]] (TFPI), which is released almost immediately after initiation of coagulation. Factor VII, which was discovered around 1950, is [[vitamin K]]-dependent and produced in the [[liver]]. Use of [[warfarin]] or similar [[anticoagulant]]s decreases hepatic synthesis of FVII.{{Citation needed|date=October 2019}}

A coagulation [[enzyme cascade]] may begin with a few molecules of factor XII and culminate in the activation of millions of times more [[fibrin]] molecules.<ref>{{cite journal | vauthors = Zhang Q, Bhattacharya S, Andersen ME | title = Ultrasensitive response motifs: basic amplifiers in molecular signalling networks | journal = Open Biology | volume = 3 | issue = 4 | pages = 130031 | date = April 2013 | pmid = 23615029 | pmc = 3718334 | doi = 10.1098/rsob.130031 }}</ref>