Koagulationskaskade

Koagulationskaskade, also known as the coagulation cascade, is a complex series of biochemical reactions that results in the formation of a blood clot. This process is essential for hemostasis, the cessation of bleeding when a blood vessel is injured. The cascade involves a series of inactive enzyme precursors, called zymogens, which are sequentially activated to form active enzymes. These enzymes then activate the next component in the series, creating a domino effect.

There are two main pathways that initiate the coagulation cascade: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway is activated by damage to the blood vessel wall itself, exposing collagen and other components that trigger the cascade. The extrinsic pathway is activated by tissue factor, a protein released from damaged cells outside the blood vessel. Both pathways converge on a common pathway that ultimately leads to the activation of thrombin.

Thrombin plays a central role in the cascade. It converts soluble fibrinogen into insoluble fibrin strands, which form a meshwork that traps blood cells and platelets, creating a stable clot. Thrombin also activates other clotting factors and platelets, further amplifying the clotting process. The entire cascade is tightly regulated by natural anticoagulants to prevent excessive clot formation, which could block blood flow. Deficiencies in any of the clotting factors can lead to bleeding disorders, while uncontrolled activation can cause thrombosis and embolism.