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Blood clotting. Dubravka Šipuš, 2nd year 2013/2014 Mentor: A. Žmegač Horvat. Hemostasis. Hemostasis – prevention of blood loss Mechanisms: Vascular constriction Formation of a platelet plug Formation of a blood clot Growth of fibrous tissue. Blood coagulation. Fast process
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Blood clotting Dubravka Šipuš, 2nd year 2013/2014 Mentor: A. Žmegač Horvat
Hemostasis • Hemostasis – prevention of blood loss • Mechanisms: • Vascular constriction • Formation of a platelet plug • Formation of a blood clot • Growth of fibrous tissue
Blood coagulation • Fast process • Procoagulants and anticoagulants • Complex cascade of chemical reactions • Blood coagulation factors
Initiation of coagulation • Formation of prothrombin activator • Extrinsic pathway • Intrinsic pathway
Prevention of blood clotting • Endothelial surface factors (smoothness, glycocalyx, thrombomodulin) • Antithrombin III-heparin cofactor • Coumarin (warfarin) • Citrate ion, oxalate
Conditions that cause excessive bleeding • Vitamin K deficiency • Diseases of the liver • Hemophilia • Thrombocytopenia
Hemophilia • Hemophilia A - abnormality or deficiency of Factor VIII • Recessive sex-linked, X chromosome disorder
References • Guyton, Hall: Textbook of Medical Physiology