Thrombomodulin-thrombin complex prevents clotting because
Thrombomodulin inhibits prothrombin activator Thrombomodulin-thrombin complex activities anti-thrombin III The binding of thrombomodulin with thrombin removes thrombin and also activities a plasma protein C which inactivates activated factors V & VIII Thrombomodulin-thrombin complex activates heparin