Platelet helps in clot stabilisation by

Ans: b (Release of calcium) Ref Khurana text book of physiologyIf activated factor XIII is given the option you can go for that. Otherwise only correct answer is calcium. Thrombosthenin is involved in clot retraction.Platelet-associated factor XIII provides a means by which to promote clot stabilization and platelet interaction with proteins of the coagulation and fibrinolytic pathways.Fibrin stabilising factor (factor XIII) which is normally present in the plasma and also released from activated platelets is activated by thrombin to form XIIla but the XIIIa in the prescence of Ca2+ causes formation of covalent crosslinkages between fibrin threads, thus adding tremendous strength to the fibrin meshwork. The fibrin meshwork traps the remaining components of plasma and blood cells to form a solid mass called clotThrombomodulin is a thrombin binding protein produced by all endothelial cells except those in cerebral microcirculation.lt converts thrombin into protein C activator (AIPGME2007)Thrombasthenin is a contractile protein present in platelet involved in clot retraction and not in stabilizationActivated factor XIII will bind to the surface of activated platelets. These platelets then participate in cell-cell or cell-clot interactions, thereby increasing the local concentration of factor XIIIa.The platelet-associated factor Xllla may increase the amount of crosslinking in a fibrin clot, thereby contributing to the aging of the clot and the reduction in the degree of platelet binding. Clot resistance to fibrinolysis is enhanced by platelet factor XEIIa-mediated crosslinking of alpha 2-antiplasmin to fibrin. The binding of factor XIIIa to the platelet surface requires the activation of the platelet fibrinogen receptor, glycoprotein Ilb-IIIa.Thus, platelet-associated factor Xllla may be used as a marker of in vivo platelet activation. Since half of the factor XIII present in blood is provided by the platelets, it is not surprising that this form of factor XIII plays an important role in hemostasis.