A major focus on hereditary disorders of coagulation occurred when hemophilia appeared in the royal families of Europe.The defect in the hemostatic mechanism found in hemophilia is only part of the complex series of reactions that participate in arresting bleeding from ruptured blood vessels. there is a platelet adhesion reaction where the platelets become sticky and bound to the endothelial connective tissue structures, including the basement membrane and collagen fibers. This leads to platelet plug formation and the platelet release reaction.In recent years, the majority of investigators working in the field of coagulation use the roman numeral nomenclature for factors V through XIII. Fibrinogen, prothrombin, calcium ions, and tissue factor are still generally referred to by their common names.In the intrinsic system, coagulation is initiated by the activation of factor XII (Hageman factor). On the other hand, the initiation of blood coagulation in the extrinsic system involves the interaction of tissue factor and factor VII. The tissue factor pathway bypasses a large number of the reactions found in the intrinsic system and enters in the coagulation cascade at the factor X level.
Under normal physiological conditions, little or no intravascular coagulation occurs. This is due to three or more effects. The first is that in flowing blood the concentration of any given coagulation factor that becomes activated is greatly reduced by dilution. A second controlling factor is the presence in plasma of numerous natural inhibitors of blood coagulation. These inhibitors inactivate coagulation enzymes, such as thrombin or factor Xa. Although these reactions are relatively slow under physiological conditions, they lead to the inactivation of activated coagulation factors and thus terminate their prolonged participation in the coagulation process. Thirdly, activated clotting factors are rapidly removed by the liver.

References

1.Earl W. Davie and Kazuo Fujikawa. Annu. Rev. Biochem. 1975.44:799-829.