Study of blood coagulation cascade and the reference values

Abstract

A harmed blood vessel begins a process denominated hemostasis. The coagulation involves a sequence of interlinked reactions, the coagulation cascade, divided in the extrinsic pathway in response to the blood contact with the extravascular tissues and in the intrinsic pathway for the blood contact with a different surface from the normal endothelium and the blood cells. Prothrombin time (PT) is the time needed to occur the coagulation, in the factors involved in the extrinsic system. Activated partial thromboplastin time (APTT) is used for verification of the coagulation intrinsic mechanism. The evaluation of coagulation cascade is reviewed in this work. Keywords: Hemostasis, coagulation, blood, prothrombin time, activated partial thromboplastin time.