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→Causes of Thrombosis
==Causes of Thrombosis==
==Causes of Thrombosis==
Thrombosis is caused by any condition that allows platelets to adhere to the endothelial wall, including:
*Damage to the vessel wall - when there is damage of the overlying endothelium, collagen is exposed and platelets will attach to this. The blood clotting process will occur, giving formation of an intraluminal blood clot. The process of formation occurs in phases giving a cross section of the clot a laminated appearance.
Vessel walls may be damaged in several ways:
#Trauma
#Localisation by colonies of bacteria
#Viral infection of endothelial cells
#Migration of parasites.
#Repeated puncture of the jugular vein is a common cause of serious or fatal thrombosis.
*Changes in normal blood flow, including stasis, turbulence, and changes in blod composition.
Stasis prevents coaglation factors being cleared by the liver and reticuloendothelial system.
Coagulation factors build up, leading to clot formation which quickly enlarges to fill the lumen. When stasis occurs in a vein, the thrombus forms behind the valve cusps.
Turbulence disrupts the laminar flow and may even damage the endothelium, allowing platelets to come into contact with the endothelial wall. Thrombi tend to form at arterial branches and venous junctions where there are eddy currents and local stasis.
Altered blood composition which can induce thrombosis includes an increase in the number and adhesiveness of platelets, or in plasma fibrin and clotting factors, resulting in a hypercoagulateable state. There may also be a decrease in the activity of the fibrinolyltic system. This may be caused by surgical or traumatic shock, or inflammation with toxaemia.
==Types of Thrombosis==
==Types of Thrombosis==