Please enable JavaScript.
Coggle requires JavaScript to display documents.
Path + CR - Ischaemia + Infarction (ii) (microscopic appearances of…
Path + CR - Ischaemia + Infarction (ii)
macroscopic appearances of infarcts
wedge-shaped (occluded vessel @ apex)
early
poorly defined
irregular
narrow rim of hyperaemia (excess blood) @ edge due to inflamm + repair
late
red or white
microscopic appearances of infarcts
not much in 1st 12-18hrs, only haemorrhaging
necrosis (condensed nuclear fragments)
acute inflamm cells (polymorphs) in between necrotic cells in 1st 24 hrs
inflamm response to necrosis @ edge after 1-2 days
phagocytosis of cellular debris + dead tissue
reparative phase
granulation tissue after 1-2 wks
then fibrous tissue (scar formation)
Consequences of fibrosis in myocardium
loss of pump function
left ventricular failure
Types of necrosis
coagulative (MI)
visible individual ghost cell outlines
liquefactive (stroke)
gangrenous
caseous (TB)
no ghost cells
fat (trauma)
factors determining degree of infarct
availability of alternative blood supply
rate of occlusion development
tissue vulnerability
neurons irreversibly damaged in 3-4 mins
myocytes in 20-30 mins
fibroblasts in hrs
O2 content of blood (anaemia increased risk of ischaemia)
Arterial disorders
atherosclerosis
arteriolosclerosis
common in DM
common in kidney
narrowing of arteriole lumen (intimal hyperplasia due to hypertension
hypertension
vasculitis
also occurs in all other blood vessels
often immune-mediated
aneurysms
types of arts
large/elastic
aorta
subclavian
common iliac
common carotid
composed of elastin + smooth muscle
affected by atherosclerosis +aneurysms
medium/muscular
coronaries
renal
composed of muscle (little elastic)
affected by atherosclerosis
small/arteriole
parenchymal
composed of smooth muscle
affected by hypertension, DM, arteriolosclerosis
Veins
low pressure blood reservoir
less muscle + elasticity
valve system needed to prevent incompetence
major disease = thrombosis (rarely atheroma)
Capills
thin wall for gas exchange
classically damaged by vasculitis, thrombi, microemboli