Lab 6 Thrombosis Embolism and Infarction Thrombosis and

Lab 6 Thrombosis, Embolism, and Infarction

Thrombosis and embolism • Thrombosis It is formation of blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. • When a blood vessel is injured platelets (thrombocytes) and fibrin form a blood clot to prevent blood loss. • Embolus is a blood clot that breaks free and travel around the body. • Embolism migration of embolus through the vasculature system to a distant site. It causes tissue damage by occlusion (closure) of blood vessels, results in hypoxia and anoxia ischaemia and infarction.

Formation of venous thrombus (thrombi) Ø venous thrombus is composed predominately of red blood cells but also platelets and leukocytes bound together by fibrin, Ø It is formed in sites of vessel damage and areas of stagnant blood flow such as the valve pockets of the deep veins of the calf or thigh, Ø Thrombi either remain in the peripheral veins, where they eventually undergo endogenous fibrinolysis and recanalization, or they embolize to the pulmonary arteries and cause pulmonary embolism (PE), which is a sudden blockage in lung artery.

Pulmonary embolism (PE) is a blockage of an artery in the lungs by a thromboembolus that has travelled from elsewhere in the body through the bloodstream. Mechanism of Pulmonary embolism • Thrombi are often formed at the large veins in the legs and pelvis due to stasis or inflammation. • The thromboembolus travels from the large vein in the leg up to the inferior vena cava, through the right side of the heart. • Then travels to the main pulmonary arteries as they branch.

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Coloured scanning electron micrograph (SEM) of a blood clot (thrombus) at a small blood vessel of a salivary gland Red blood cells (erythrocytes, red) are trapped within a fibrin protein mesh (threadlike), which is formed in response to chemicals secreted by platelets, fragments of white blood cells (large, round). Clots are formed in response to cardiovascular disease or injuries to blood vessels. Magnification: x 1650.

Myocardial Infarction – is tissue death (necrosis) caused by a reduction / stoppage in blood flow due to artery blockages, mechanical compression, rupture, or vasoconstriction. Myocardial Infarction is commonly known as a heart attack, the interruption of blood supply to part of the heart, causing some heart cells to die. �Most patients who sustain an MI have coronary atherosclerosis. �The thrombus formation occurs most often at the site of an atherosclerotic lesion, thus obstructing blood flow to the myocardial tissues.

Myocardial Infarction �Plaque rupture is believed to be the triggering mechanism for the development of the thrombus in most patients with an MI. �When the plaques rupture, a thrombus is formed at the site that can occlude blood flow, thus resulting in an MI.

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