Final answer:
Platelet plug formation is part of hemostasis and involves the adhesion and aggregation of platelets to form a temporary plug at the site of blood vessel injury, which is later reinforced by fibrin during coagulation.
Step-by-step explanation:
Platelet Plug Formation and Its Steps
Platelet plug formation is a crucial step in hemostasis, which is the process that stops bleeding from a damaged blood vessel. The plug formation entails two steps. Firstly, there is the adhesion of platelets to the exposed collagen fibers at the site of the vessel injury. Upon contact with the damaged vessel, they change shape and become spiked and sticky, allowing them to adhere to the collagen. This is possible partly due to the presence of von Willebrand factor, which helps to stabilize the adhesion of the platelets to the vessel wall.
In the second step, called aggregation, additional platelets are attracted to the site of injury, adhering not only to the vessel but also to one another, forming a mass known as a platelet plug. These platelets release chemicals that further promote hemostasis. Together, these steps—adhesion and aggregation—lead to the formation of a temporary platelet plug, which is subsequently reinforced by fibrin strands during coagulation, creating a durable blood clot.