Blood clotting anticoagulation systems

Normal hemostasis is a balance between excessive and inadequate blood clotting. Overactive blood clotting is harmful because of the tendency for thrombus formation and occlusion of arteries and veins. Vessels may become directly blocked by the thrombus, or a portion of the thrombus may break off and create an embolism that lodges elsewhere in the vascular system. The tendency for excessive thrombus formation in the venous system is usually treated with anticoagulant drugs such as heparin and warfarin. Platelet inhibitors such as aspirin help prevent arterial thrombogenesis. Thrombolytic drugs (streptokinase, t-PA) that facilitate the dissolution of harmful clots may successfully reopen... 

The hbrinolytic system (Fig. 22.2) is involved in restricting clot propagation in the blood and in the removal of fibrin as wounds heal. Treatment of patients with hbrinolytic (thrombolytic) drugs that activate the hbrinolytic system is not a substitute for the anticoagulant drugs. The purpose of thrombolytic therapy is rapid lysis of already formed clots. 

The two major kinds of samples analyzed for xenobiotics exposure are blood and urine. Both of these sample types are analyzed for systemic xenobiotics, which are those that are transported in the body and metabolized in various tissues. Xenobiotic substances, their metabolites, and then-adducts are absorbed into the body and transported through it in the bloodstream. Therefore, blood is of unique importance as a sample for biological monitoring. Blood is not a simple sample to process, and subjects often object to the process of taking it. Upon collection, blood may be treated with an anticoagulant, usually a salt of ethylenediaminetetraacetic acid (EDTA), and processed for analysis as whole blood. It may also be allowed to clot and be centrifuged to remove solids the liquid remaining is blood serum. 

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