L20: Embolism, Ischaemia, Infarction Flashcards
How would you distinguish grossly between a thrombus and a thromboembolus?
Search for thrombus upstream
Where do most venous thromboemboli become trapped?
GIT, splenic, pancreatic mesenteric veins/ portal vein –> vascular bed of liver
Venous thromboemboli elsewhere –> lungs
What is a consequence of septic thromboembolism?
New foci infection
What are the possible consequences of pulmonary thromboembolism?
Doesn’t usually cause infarction due to dual blood supply
but may occlude pulmonary artery –> cor pulmonate
List other types of emboli besides thromboemboli.
Bacterial colonies/ malignant neoplastic cells/ lipid
Foreign bodies, parasites, fibrocartilage, tissue cells, agglutinated erythrocytes , gas bubbles (Nitrogen)
What is meant by the terms ischaemia, infarction and infarct?
Ischaemia= hypoxic/ anoxic injury resulting from local reduction blood flow Infarction= process where ischaemic necrosis of local area develops Infart= area of infarcted tissue
What are some conditions other than thrombosis, thromboembolism or embolism that can cause ischaemia?
• Congestive heart failure • Shock • Dehydration • Impaired venous return to right heart (e.g. bloat) External compression of vessels
Why is infarction more commonly referable to arterial obstruction than to venous obstruction?
Many tissues lack a collateral arterial blood supply whereas collateral venous channels may be numerous
What are the major factors that determine the prognosis for an animal that has a local reduction in blood flow?
• Availability of alternative blood supply of oxygen
• Rate of development/ degree –> sudden and acute usually causes infarction
• Size of affected vessel
• Cell vulnerability to hypoxia
• Duration of hypoxia
Oxygen content of blood
Why are infarcts less likely to develop in the lungs or liver than in other organs?
Lungs are supplied with both pulmonary and bronchial arteries
Liver receives blood from hepatic artery and portal vein
what are the brain neuron, myocardial fibre, renal proximal tube and small intestinal cells vulnerability to hypoxia?
brain neurons - 3 - 4 min
myocardial - 20 - 30 min
renal proximal - 2 hr
small intestine epic - 5 - 10 min, crypt cells 2 - 4 hr
where is coagulative necrosis caused by infarct commonly seen?
in almost all tissue excluding spinal cord and brain
where is liquefaction necrosis caused by infarct commonly seen?
brain and spinal cord
what is a saddle thromboembolism?
when a thromboembolism lodges at the site of vessel bifurcation
