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Western University
Pathology 3240A
Craig Hall

Disturbances of Blood Flow and Body Fluids 2 Vascular Hemodynamics ­ blood flow – normal fluid homeostasis o edema o hyperemia o hemorrhage ­ maintenance of blood as a liquid o thrombosis ­ embolism ­ infarction ­ schock Hyperemia and Congestion ­ both indicate a local increased volume of blood in a particular tissue ­ Hyperemia o Active process o Dilation of arteries/arterioles results in increased blood flow (perfusion) of  a tissue or organ o More blood going to the area o Usually equal amounts of blood on both sides  But now more blood from artery side (increased inflow) o Ex. Exercise, inflammation  Physiological and pathological o Increased oxygenated blood going to specific area o Tissue appears red  Because of engorgement with oxygenated blood o Redness  Acute inflammation o Skeletal muscle during exercise ­ Congestion o Passive process o Impaired venous drainage results in stasis and the accumulation of  deoxygenated blood o Due to increased venous hydrostatic pressure o Blood movement slower than usual S ▯ tasis  Increased hydrostatic pressure  Decreased outflow o The tissue has a bluish tinge due to the accumulation of deoxygenated  hemoglobin o Ex.  Cardiac failure (congestive heart failure) – systemic (in internal  organs)  Isolated venous obstruction • Thrombophlebitis: inflammation of the veins s▯ tasis of the  blood o Internal condition: congestive passive congestion of the liver secondary to  right heart failure Normal Hemostasis ­ a consequence of tightly regulated processes that maintain blood in a fluid, clot  free state in normal vessels ­ the pathological form of hemostasis is thrombosis o formation of blood clot o injury to blood vessels ­ blood  ▯fluid state depends on: o integrity of vessels (vascular wall) o normal blood flow o normal blood viscosity  more platelets (plasma)  ▯more viscous o normal blood composition  platelets and coagulation factors • if too much platelets  ▯more blood clot formation • coagulation factor – active when injury to blood vessels,  process that results in formation of blood clot Thrombosis ­ formation of mass/clotted blood in the heart or blood vessels (anywhere in  circulatory system ­ Causes: o Vessel wall damage/endothelial injury  Trauma  Inflammation o Abnormal blood flow  Stasis • Lack of activity, prolonged bed rest • Decreased cardiac output • Increased blood viscosity o Dehydration o Change in blood composition  Increased platelets ­ Thrombus Consists of: o RBC o WBC o Platelets o Fibrin network  From the fibroblasts o End up with obstruction of blood vessel ­ Appearance of Thrombus o Alternating layers of platelets and fibrin with darker erythrocyte rich  layers o Adherent to the luminal surface of the vessel o Look different on arteriole and venous side o Dark areas – RBCs o Light areas – platelets o Deep venous thrombosis  Takes shape of blood vessel  Very dark red  Mainly RBCs ­ Outcome of Thrombosis o Lysis (dissolution)  Happened, destroyed o Propagation  Enlargement and extension of thrombus o Organization  Fibrosis of thrombus o Recanalization  During organization new channels may form within the thrombus o Breakdown into emboli ­ Complication of Thrombi o Fragments of thrombus break off and result in  thromboembolization/emboli  Mass in circulation  Stops somewhere depending on size o Reduced blood flow to a tissue/organ resulting in ischemic injury or  infarction ­ Embolism o Process called embolization
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