Final answer:
Tissue factor is released after injury and initiates the extrinsic pathway which, in turn, leads to the activation of the common pathway for blood clot formation.
Step-by-step explanation:
Tissue factor, also known as protein thromboplastin, is released after injury and it initiates the extrinsic pathway of blood coagulation. The extrinsic pathway is a quicker responding and more direct pathway that begins when there is damage to the surrounding tissues. This leads to the release of factor III (thromboplastin) from the damaged extravascular cells, which are extrinsic to the bloodstream.
Upon its release, in the presence of calcium ions (Ca²⁺), factor III activates factor VII, which then combines with other factors to form an enzyme complex that activates factor X. The activation of factor X marks the transition into the common pathway, where the formation of a blood clot occurs through a series of steps involving the conversion of prothrombin to thrombin, and finally, the conversion of fibrinogen to insoluble fibrin strands, which stabilizes the clot.