Thrombomodulin-thrombin complex prevents clotting because
The endothelium of the blood vessels also plays an active role in preventing the extension of clots. All endothelial cells except those in the cerebral microcirculation produce thrombomodulin, a thrombin-binding protein, on their surfaces. In circulating blood, thrombin is a procoagulant that activates factors V and VIII, but when it binds to thrombomodulin, it becomes an anticoagulant in that the thrombomodulin-thrombin complex activates protein C. Activated protein C (APC), along with its cofactor protein S, inactivates factors V and VIII and inactivates an inhibitor of tissue plasminogen activator, increasing the formation of plasmin.Ref: Ganong&;s Review of medical physiology 25th edition. Page: 565
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
Cardiovascular system