The role of platelets in physiological hemostasis

Functions of platelets in physiological hemostasis:

1. Adhesion and aggregation: Platelets can rapidly adhere to the injured vascular wall and form a platelet plug through aggregation, directly sealing the vascular rupture site to achieve initial hemostasis.

2. Release of procoagulant substances: Upon stimulation, platelets release various procoagulant substances, such as platelet factor III, which accelerate the blood coagulation process and promote the conversion of fibrinogen to fibrin, thereby enhancing the stability of the hemostatic plug.

3. Contractile function: Platelets also possess contractile ability, enabling the blood clot to further contract and fill the bleeding site, enhancing the hemostatic effect.

Repair of injured vessels: Platelets can secrete growth factors that promote endothelial cell migration and proliferation, aiding in the repair and regeneration of damaged blood vessels.

4. Reduction of inflammatory response and prevention of infection: Platelets have immunomodulatory effects; they can release various chemokines and cytokines that inhibit leukocyte migration and activation, alleviate local inflammatory responses, and enhance the body's defense against bacteria and other pathogens by releasing antimicrobial peptides and pro-inflammatory mediators, thus reducing the risk of infection.

Therefore, abnormalities in platelet number or function, such as thrombocytopenia or platelet dysfunction, will directly affect the physiological hemostasis process and increase the risk of bleeding.