<unk>  <unk>  is produced by the liver and circulates as a homo-dimer in its inactive form. The plasma half-life of<unk>  is approximately 52 hours. The zymogen<unk> s activated into<unk> a by<unk> Ia <unk> Ia), thrombin, and<unk> a itself; due to its activation by<unk> Ia,<unk>  is a member of the "contact pathway" (which includes HMWK, prekallikrein,<unk> I,<unk> , and<unk> X).<unk> a activates<unk> X by selectively cleaving arg-ala and arg-val peptide bonds.<unk> Xa, in turn, forms a complex with<unk> IIa (FIXa-FVIIIa) and activates<unk>  Inhibitors of<unk> a include protein Z-dependent protease inhibitor (ZPI, a member of the serine protease inhibitor/serpin class of proteins), which is independent of protein Z (its action on<unk>  however, is protein Z-dependent, hence its name).
Factor XI
Factor VIII
Factor VIII 
Factor IX
Thrombin
Prothrombinase
Von Willebrand factor
Fibrinogen