intrinsic pathway of blood coagulation
Last reviewed 01/2018
After initiation, each step in the intrinsic pathway is catalysed by the product of the preceding step:
- factor XII, also termed Hageman factor, is converted to XIIa on contact with negatively-charged surfaces e.g. that of subendothelial collagen. For activation to its enzymatic form, it requires high molecular weight kininogen and prekallikrein.
- factor XIIa converts factor XI to XIa
- factor XIa converts factor IX converted to IXa
- factor IXa converts factor X to Xa; to do this it requires:
- calcium ions
- factor VIIIa
- a negatively charged surface; in vivo, this is the surface of platelets so localizing the cascade
- factor Xa then activates the common pathway of coagulation
role of factor VIII in blood coagulation
role of factor IX in blood coagulation
common pathway of blood coagulation