Platelet adhesion receptors and their participation in hemostasis and thrombosis

Circulating blood platelets survey the integrity of the vascular wall and r espond after tissue trauma to control hemorrhage. During the initial respon se to vascular injury platelets adhere to injured surfaces and aggregate to form a platelet plug or thrombi. However, the complete arrest of hemorrhag e depends not only upon platelets but other factors, as well, collectively referred to as hemostasis. For normal hemostasis to occur platelets along w ith the blood coagulation cascade act cooperatively to arrest blood flow. N evertheless, platelets within the blood clot are of paramount importance as evidenced by the critical bleeding occurring with a reduced platelet count , a condition referred to as thrombocytopenia. Moreover, the same processes occurring under normal circumstances to prevent hemorrhage may also interf ere with blood flow in atherosclerotic arteries and cause life-threatening situations, such as myocardial infarction, the leading cause of death in de veloped countries. Thus, normal platelet function involves maintaining a ba lance between preventing excessive blood loss and allowing essential blood flow to critical tissues and organs. (C) 2001 Prous Science. All rights res erved.