How does ADP

Platelet aggregation

1 definition

Platelet aggregation refers to the agglomeration or clumping of blood platelets (thrombocytes) as part of primary hemostasis.

2 physiology

Platelet aggregation is preceded by activation of the platelets, which is triggered by the contact of the von Willebrand factor or its receptors (GP Ib-V-IX complex and GP IIb / IIIa complex) with exposed collagen components of the vascular wall. This phase is also known as platelet adhesion ("platelet accumulation"). This first phase of adhesion is stabilized by collagen, fibronectin, laminin and integrin receptors on the platelet surface.

Activation leads to a morphological change in the platelets. They increase their surface area by restructuring their cytoskeleton, everting and degranulating pseudopodia. Among other things, ADP, PAF and Thromboxane A2 (TXA2) distributed. Since platelets themselves have receptors for these messenger substances, ADP binds to the P2Y12- and P2Y1Receptors, from PAF to the PAF receptor and from TXA2 to the thromboxane receptor α (TPα) in the sense of positive feedback on the activation of further platelets.

The granule contents that are poured out also induce induction

Platelet aggregation takes place after ADP-dependent activation of the GP IIb / IIIa receptor through fibrin-mediated cross-linking of the platelets.

see also:Antiplatelet drugs

3 pathology

There are rare, congenital diseases that result in impaired platelet aggregation, including Glanzmann's thrombasthenia.

see also:Thrombocytopathies

4 laboratory method

In the hemostasis laboratory, platelet aggregation is a method for examining platelet function, Born aggregometry.