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A thrombus, or colloquially a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets that form a platelet plug, and a mesh of cross-linked fibrin protein. The substance making up a thrombus is sometimes called cruor. A thrombus is a healthy response to injury intended to prevent bleeding, but can be harmful in thrombosis, when clots obstruct blood flow through healthy blood vessels. Mural thrombi are thrombi that adhere to the wall of a blood vessel. They occur in large vessels such as heart and aorta, and can restrict blood flow but usually do not block it entirely. They appear grey-red with alternating light and dark lines (known as lines of Zahn) which represent bands of fibrin (lighter) with entrapped white blood cells and red blood cells (darker). ==Cause== Virchow's triad describes the pathogenesis of thrombus formation: # Endothelial injury (injury to the endothelial cells that line enclosed spaces of the body, such as the inside of blood vessels) (e.g. trauma, atheroma) # Abnormal blood flow (loss of laminar flow resulting from stasis in veins or turbulence in arteries) (e.g. valvulitis, aneurysm) # Hypercoagulability (e.g. leukaemia, Factor V mutation (Leiden)) Disseminated intravascular coagulation (DIC) involves widespread microthrombi formation throughout the majority of the blood vessels. This is due to excessive consumption of coagulation factors and subsequent activation of fibrinolysis using all of the body's available platelets and clotting factors. The end result is hemorrhaging and ischaemic necrosis of tissue/organs. Causes are septicaemia, acute leukaemia, shock, snake bites, fat emboli from broken bones, or other severe traumas. DIC may also be seen in pregnant females. Treatment involves the use of fresh frozen plasma to restore the level of clotting factors in the blood, platelets and heparin to prevent further thrombi formation. Thoracic aortic thrombus is a rare pathology that usually originates from an atherosclerotic aortic wall lesion or an aortic aneurysm and is a potential source of visceral, cerebral and peripheral embolism. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「thrombus」の詳細全文を読む スポンサード リンク
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