Verenhyytymistekijät

Verenhyytymistekijät, also known as coagulation factors, are a group of proteins circulating in the blood plasma that are essential for hemostasis, the process by which bleeding is stopped. When a blood vessel is injured, these factors are activated in a cascade, a series of enzymatic reactions where each factor activates the next. This cascade culminates in the formation of a fibrin clot, a mesh-like structure that seals the injured vessel and prevents further blood loss.

There are numerous coagulation factors, each designated by a Roman numeral, from I to XIII, although some numbers are no longer in use or have been reclassified. For instance, factor I is fibrinogen, which is converted into fibrin by thrombin (factor IIa). Factor VIII and factor IX are crucial in the intrinsic pathway of coagulation, and their deficiency leads to hemophilia A and B, respectively, conditions characterized by excessive bleeding. Factor VII, along with tissue factor, initiates the extrinsic pathway. Factor XIII is a transglutaminase that stabilizes the fibrin clot by cross-linking fibrin strands, making it more resistant to degradation.

The coagulation system is tightly regulated to prevent excessive clotting (thrombosis) or insufficient clotting (bleeding disorders). Anticoagulant proteins, such as antithrombin and protein C, counteract the procoagulant factors. Disruptions in the balance of this system can have serious health consequences.