Final answer:
The extrinsic pathway of clotting can be initiated without tissue damage, while the intrinsic pathway is triggered by internal damage to the vessel wall. Both pathways lead to the common pathway, resulting in the formation of a blood clot.
Step-by-step explanation:
The extrinsic pathway of clotting can be initiated without tissue damage. This pathway is triggered by trauma or damage to the tissues surrounding the blood vessels. When the damaged extravascular cells come into contact with blood plasma, they release thromboplastin, also known as tissue factor, which initiates the extrinsic pathway.
The intrinsic pathway, on the other hand, is initiated within the bloodstream and is triggered by internal damage to the vessel wall.
Both the extrinsic and intrinsic pathways lead to the common pathway of clotting, which ends in the formation of a blood clot. The common pathway involves several coagulation factors, such as factor X, factor V, and fibrinogen, which work together to produce a stable blood clot.