Library · Molecule
Fibrin
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Fibrin is not floating around in the blood waiting. What floats around is its earlier version, fibrinogen, and it only becomes fibrin when it is needed: the common coagulation pathway activates it, and the final order comes from an enzyme called thrombin.
Once formed, the fibrin pieces attract one another and join into strands. Those strands tie down the platelets, the cells that had already piled up at the wound, and stabilize what is called the platelet plug.
Then comes factor XIII, which works on those strands until it forms a fibrin mesh, a firm net instead of loose threads.
Think of a sand plug with cement poured over it. And the same thrombin that turns fibrinogen into fibrin also activates plasminogen and turns it into plasmin, the enzyme that will later break down the mesh.
In brief
Fibrin comes from fibrinogen: the common coagulation pathway activates it and turns it into fibrin, and thrombin is what gives that order.
Its subunits have an affinity for one another and join into strands that tie down the platelets and stabilize the platelet plug.
A sand plug with cement poured over it.
Factor XIII acts on those strands to form a fibrin mesh.
That same thrombin activates plasminogen to plasmin, which will later break down that mesh.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Coagulation Pathways, StatPearlsPublished
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