Final answer:
The statement is false as hemostasis usually involves both the intrinsic and extrinsic pathways converging at a common pathway to form a blood clot. The intrinsic pathway is often initiated by internal factors, while the extrinsic pathway starts by external tissue damage.
Step-by-step explanation:
True or false: In most cases of bleeding, only the intrinsic mechanism of coagulation is activated. This statement is false. The hemostatic process consists of three general steps: vascular spasm, platelet plug formation, and coagulation, leading to the synthesis of fibrin which eventually forms a blood clot. While the intrinsic pathway can be triggered by internal factors and contact with negatively charged surfaces, the extrinsic pathway is commonly initiated by tissue damage, releasing tissue factors. Both pathways converge at the common pathway, where factor X activates to form thrombin, which then transforms fibrinogen into fibrin. Especially with external bleeding, both intrinsic and extrinsic pathways are generally activated to ensure effective hemostasis.
Furthermore, disorders such as hemophilia illustrate inadequate clotting and underscore the importance of multiple pathways leading to blood clot formation. The presence of thrombi or emboli can indicate excessive clotting, emphasizing the need for a balanced coagulation process.