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17 Cards in this Set
- Front
- Back
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What is meant by the terms embolus?
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an intravascular, solid, liquid or gaseous mass that is transported by the blood to a site distant from its point of origin
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What is meant by the terms embolism?
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the blockage of a downstream vessel by an embolus arising upstream
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What is the most common type of embolus?
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thromboemboli
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What is meant by the term saddle thromboemboli?
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thromboemboli lodge at sites of vessel bifurcation (分岐点)
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What is meant by the terms bland and septic thromboemboli?
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thrombus is sterile in bland thromboemboli
in septic thromboemboli, thromus is containing infectiuos agents such as bacteria |
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What are the potential consequences of pulmonary thromboembolism?
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If teh size of the thromboembolus is lare, it may occlude the main pulmonary artery.
if >60% of the pulmonary circulation is obstructed by an embolus → sudden death, right heart failure (cor pulmonale) or cardiovascular colapse multiple emboli over time → pulmonary hypertension and cor pulmonale |
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What are the potential consequences of systemic thromboembolism?
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it is likely to be widely distributed and cause infarction of tissue in the supply area of the ebstructed vessels
The consequences depend on the presence of collateral circulation in the affected tissue, the tissue's vulnerability to hypoxia and the calibre of the vessel occluded |
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List other types of emboli besides thromboemboli
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●fat emboli
●gas emboli ●foreign bodies ●neoplastic cells ●parasites ●fibrocartilaginous emboli ●amniotic fluid ●bacterial and fungal emboli ●miscellaneous emboli |
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What is meant by the terms ischaemia?
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hypoxic or anoxic tissue injury resulting from a local reduction in blood flow
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What is meant by the terms infarction?
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ischaemic coagulative necrosis of a localised area of tissues
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What is meant by the terms infarct?
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the area of tissue which has undergone infarction
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What conditions potentially lead to ischaemia?
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●functional reduction in blood flow (eg:cardiac failure, dehydration)
●obstruction of blood flow (eg: thrombosis or embolism, degeneration fo a vessel wall) |
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Why is infarction more commonly referable to arterial obstruction that venous obstruction?
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because there are more numerous collateral venous channels than there are collateral arterial channels
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What are the major factors that determine the outcome of occlusion of a blood vessel?
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●nature of the blood supply: the availability of an alternative blood supply-functional end arteries? parallel systems? or dual blood supply?
●rate of development and degree of impairment of blood flow: sudden? or slow?- slow→less significant ●size of the affcted vessels: smaller → less signimicant ●tissue vulnerability to hypoxia and duration of hypoxia: CNS, neurons, SI, myocardial fibres → less susceptable ●oxygen content of the blood: the overall cardiocvascular and haematological health of an individual ●miscellaneous factors: reperfusion injury, metabolic waste products etc. |
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Which organs or tissues are most vulnerable to hypoxic injury?
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CNS neurons; neurons and oligodengroglia
amonst neurons, cerebellar Purkinje cells and deep laminar neurons of the cerebral cortes are most sensitive |
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What gross features would allow you to recognise an infarct at surgery or necropsy?
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●wedge-shaped with te occluded vessel at the apex
●if the base is a serosal surface, there is often fibrinous exudate over the surface red or white discolouration of tissues |
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How does the gross appearance of an infarct alter over time?
(i.e. acute vs chronic) |
●paraacute: invisible
●acute: friable, red and white infarcts are distincitve, a narrow zone of inflammatory band ●chronic: periphearl inflammation becomes more prominent, advancing inwards ●chronic: leukocyte invation → progressive liquefaction and phagocytosis of the mecrotic debris, ultimately replaced by scar tissue with the zone remaining as a firm, contracted, pale zone |
