What is the second stage of hemostasis?

The second stage of hemostasis is characterized by the activation and aggregation of platelets, making the platelet phase the correct answer. During this stage, platelets adhere to the site of vascular injury and to each other, forming a temporary "platelet plug" to reduce blood loss. This is critical because it helps quickly stabilize the area until the next stage, where a more stable clot is formed through the coagulation cascade.

Understanding this phase is essential, as it plays a pivotal role in the body's immediate response to vascular injury. The other stages of hemostasis—vascular phase and coagulation phase—are important, but they occur either before or after the platelet phase and do not specifically capture the unique actions and processes that take place during the second stage. The fibrinolysis phase also happens later when the clot is dissolved after healing has occurred, which further supports that it cannot be the second stage.