Ischaemia And Infarction Flashcards
Ischaemia definition
Decreased blood supply to an organ resulting in hypoxic damage to susceptible cells
Pathophysiology of ischaemia
Lack of oxygen»_space; oxidative metabolism stops» refuction in ATP» anaerobic glycolysis takes over» stores of glucose and glycogen depleted» anaerobic glycolysis slows and stops(inhibited by low levels of ATP) , membrane pump failure , influx of sodium and water into cell
Reperfusion following ischaemia
Promote recovery of cells if reversibly injured or exacerbate cell injury
Patterns of necrosis
Coagulative, liquefactive, gangrenous, caseous , fat and fibrinoid
Infarction
Area of ischaemic necrosis due to occlusion of arterial supply or venous drainage
Infarction common sites
MycodiaL
Pulmonary
Bowel
Extremities
Infarction pathogenesis
Arterial occlusion
Arterial narrowing
Venous occlusion
Arterial occlusion
Main cause :embolism & thrombosis.
Effects depends on anatomy of an organ’s arterial supply.
Other causes vasospasm.
Arterial narrowing
Can cause frank infarctiom or only ischaemic effects.
It allows time for collateral blood supply to develop if occlusion builds up slowly
Venous occlusion
If bypass channels available
Congestion > opening of bypass channels> arterial inflow restored.
If single outflow vein, blood able to pump in via arteries but cannot exit via veins. Pressure increases> can eventually exceed arterial pressure> necrosis
Morphology of an infarction. (Colour, presence or absence of infection)
Red/White.
Presence/ absence: septic/bland
Red infarcts
Falls under which pathogenesis?
Venous occlusion.
Red infarcts
How will the blood collect in loose tissues?
Blood collects in infarcted zone
Red infarcts
What happens in tissues with dual circulation?
Blood flow into necrotic zone
Pulmonary infarct as an example of red infarct why is it a red infact?
It is haemorrhagic because of the dual blood supply. Some blood still flows from the non-occluded bronchial arteries but does not prevent infarction
