Final answer:
The extrinsic pathway of coagulation is initiated by the release of tissue thromboplastin due to tissue damage, leading to activation of factor X and the common pathway, resulting in blood clot formation.
Step-by-step explanation:
The pathway of coagulation initiated by the release of tissue thromboplastin as a result of tissue damage is known as the extrinsic pathway. This pathway is generally much quicker and occurs when the damaged extravascular cells, which are extrinsic to the bloodstream, release tissue factor or factor III (thromboplastin) upon contact with blood plasma. Following this release, calcium ions (Ca²⁺) and factor VII (proconvertin), which is activated by factor III, form an enzyme complex that ultimately leads to the activation of factor X (Stuart-Prower factor). Activation of factor X then leads to the common pathway of coagulation, which results in the formation of a blood clot.
The common pathway is the final coagulation pathway that can be activated either by the intrinsic or extrinsic pathway and is responsible for the formation of fibrin that seals off the vessel and stabilizes the blood clot.