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From Biology-Online Dictionary
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noun, plural: fibrinogens

A soluble rod-shaped plasma glycoprotein (340 kd, 46 nm long) consisting of six peptide chains (two each of A_, B_ and _) and is involved in blood clot formation, particularly by converting into insoluble fibrin strands following the activation of thrombin


Coagulation, the process of clot formation, involves platelet and blood clotting factors. In humans, the coagulation mechanism is comprised of two processes, i.e. the primary hemostasis and the secondary hemostasis. The latter entails two pathways: (1) intrinsic pathway (contact activation pathway) and (2) extrinsic pathway (tissue factor pathway). Both pathways lead to the formation of fibrin.

Fibrinogen, also called as clotting factor I, is a soluble, plasma glycoprotein (340 kd, 46 nm long) consisting of six peptide chains (two each of A_, B_ and _). The liver is the source of fibrinogen. The hepatocytes are cells in the liver that synthesize fibrinogen.

Fibrinogen is involved in fibrin formation (i.e. on the latter phase of blood clot formation). Its activator is thrombin, converting the soluble fibrinogen into insoluble fibrin, i.e. long strands in a mesh network during clot formation.

The normal level of fibrinogen in human blood plasma is 200-400 mg/dL. Some of the genetic disorders associated with fibrinogen include congenital afibrogenmia and familial renal amyloidosis.

Also called:

  • clotting factor I
  • coagulation factor I

See also: