Case Study#6   1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16   Activation of Factor X Cleavage of a peptide bond in the amino end of the heavy chain by either: VIIa-TF IXa-VIIIa   Factor X Downregulation 1. Tissue Factor Pathway Inhibitor (TFPI) - Xa binds to TFPI to form a complex and inactivate Xa Xi - TFPI/Xi then inactivates VIIa/TF by forming a quaternary, inactive complex 2. Antithrombin (AT) - Forms stable complex with Xa, cleared by liver - Heparin accelerates AT-Xa complex formation