Which phase of hemostasis involves primary aggregation of platelets?

Which phase of hemostasis involves primary aggregation of platelets?

• A. Mechanical phase
• B. Chemical phase
• C. Cellular phase
• D. Coagulation phase

Answer: (A)

The phase of hemostasis that involves the primary aggregation of platelets is indeed the mechanical phase. During this initial stage of hemostasis, vascular injury occurs, leading to the exposure of the underlying collagen and tissue factor in the vessel wall. Platelets are quickly activated and adhere to the exposed site, primarily through the interaction of platelet surface receptors and von Willebrand factor. This adhesion triggers platelet activation and results in the release of chemical signals that further attract and activate additional platelets. These platelets then aggregate at the site of injury to form a temporary "platelet plug," which helps to seal wounds and prevent further bleeding. This phase is crucial for establishing a rapid response to vascular injury and occurs before the more complex processes of coagulation take place. In contrast, the other phases involve different mechanisms or stages of hemostasis. The chemical phase refers to the cascade of reactions that lead to fibrin formation, while the cellular phase involves the interaction of various blood cells and components in the hemostatic process. The coagulation phase is focused on the activation of coagulation factors that ultimately stabilize the platelet plug with fibrin, which is a later step in the hemostatic process.

The phase of hemostasis that involves the primary aggregation of platelets is indeed the mechanical phase. During this initial stage of hemostasis, vascular injury occurs, leading to the exposure of the underlying collagen and tissue factor in the vessel wall. Platelets are quickly activated and adhere to the exposed site, primarily through the interaction of platelet surface receptors and von Willebrand factor. This adhesion triggers platelet activation and results in the release of chemical signals that further attract and activate additional platelets.

These platelets then aggregate at the site of injury to form a temporary "platelet plug," which helps to seal wounds and prevent further bleeding. This phase is crucial for establishing a rapid response to vascular injury and occurs before the more complex processes of coagulation take place.

In contrast, the other phases involve different mechanisms or stages of hemostasis. The chemical phase refers to the cascade of reactions that lead to fibrin formation, while the cellular phase involves the interaction of various blood cells and components in the hemostatic process. The coagulation phase is focused on the activation of coagulation factors that ultimately stabilize the platelet plug with fibrin, which is a later step in the hemostatic process.