Final answer:
The intrinsic pathway is initiated by factor XII coming into contact with foreign materials, while the extrinsic pathway is triggered by damage to surrounding tissues. Both pathways converge into the common pathway where fibrin is produced to form a blood clot.
Step-by-step explanation:
The intrinsic pathway (also known as the contact activation pathway) is a longer and more complex pathway of coagulation. It is initiated when factor XII (Hageman factor) comes into contact with foreign materials, such as a blood sample being put into a glass test tube. This pathway involves a series of reactions that activate factors XI, IX, and X, leading to the common pathway where fibrin is produced to form a blood clot.
The extrinsic pathway (also known as the tissue factor pathway) is a quicker and more direct pathway that is triggered by damage to the surrounding tissues, such as in a traumatic injury. It involves the release of factor III (thromboplastin) from damaged cells, which leads to the activation of factor X and the common pathway.
Both the intrinsic and extrinsic pathways converge into the common pathway, where factor X is activated and leads to the production of thrombin and fibrin, resulting in the formation of a blood clot.