| thrombi | Plural of thrombus. (05 Mar 2000) |
|---|---|
| thrombin | <enzyme> Protease (34 kD) generated in blood clotting that acts on fibrinogen to produce fibrin. Consists of two chains, A and B, linked by a disulphide bond. B chain has sequence homology with pancreatic serine proteases: cleaves at Arg Gly. Thrombin is produced from prothrombin by the action either of the extrinsic system (tissue factor + phospholipid) or, more importantly, the intrinsic system (contact of blood with a foreign surface or connective tissue). Both extrinsic and intrinsic systems activate plasma factor X to form factor Xa which then, in conjunction with phospholipid (tissue derived or platelet factor 3) and factor V, catalyses the conversion. (18 Nov 1997) |
| thrombin time | Test of the conversion of fibrinogen to fibrin by thrombin in which clotting time of plasma mixed with a thrombin solution is measured. Time is prolonged by afibrinogenaemia, abnormal fibrinogen, or the presence of inhibitory substances, e.g., fibrin-fibrinogen degradation products, heparin. Reptilase, a thrombin-like enzyme unaffected by the presence of heparin, may be used in place of thrombin. (12 Dec 1998) |
| thrombinogen | A coagulation factor needed for the normal clotting of blood. In the cascade of events leading to the final clot, thrombinogen precedes thrombin (and so is a precursor to thrombin). In fact, thrombinogen gives rise to thrombin, and also called prothrombin. (12 Dec 1998) |
| thrombinogenesis | Thrombin production. (05 Mar 2000) |