w5 histology Flashcards
why is the subendocardial space is most susceptible to ischemia
Greater dependence on diastolic perfusion
Greater energy demand—the internal-most myocytes have higher energy expenditure because they shorten more than cardiomyocytes in more superficial regions of the myocardium
Because the subendocardial plexus is the last to receive blood, oxygen tension is lowest in this region of the heart
what are the three lays in valves
Atrialis (AV)/ventricularis (semilunar)
Lines the inflow surface
Spongiosa
Fibrosa
Continuous with cordae tendinea
how can fibrosis induce arrthymias
through thr redistribution of gap junctions
what kind of filaments make up adherins and desmosones
adherins-actin
desmosomes- intermediate
how can a mutation in the intercalated disks lead to sudden cardiac death
In some types of cardiomyopathy, the cardiomyocytes become highly branched, a finding called fiber disarray.Patients with this type of cardiomyopathy are highly susceptible to sudden cardiac deathdue to arrhythmias resulting from the irregular pattern of action potential propagation through the excessively branched cells
what type of junction is associated with intercalated disks
gap junctions
what cells contribute to atheroma cap formation
VSMC dedifferentiate and go into intima and then secrete collagen and contribute to this formation
describe the three different plaque changes
Rupture:occurs when the cap gives way releasing the highly thrombogenic contents of the necrotic lipid core into the circulation
Erosion:occurs when turbulent flow around the cap strips away the endothelial cells lining the vessel; this exposes the subendothelial connective tissue, which is also highly thrombogenic
Hemorrhage into the atheroma: The increased wall thickness increases the distance oxygen and nutrients have to diffuse to supply cells in the wall. Hypoxia causes neovascular growth from the vasa vasorum. These new vessels are prone to leak and burst releasing blood into the atheroma. This can cause the atheroma to swell rapidly and occlude the lumen. In some, but not all, cases this may lead to atheroma rupture
how long does it take contractility to cease after blockage
when is cardiac injury irreversible
when does microvascular injury occur
when is 90% of ATP depleted
2 mins
20-40 mins
1 hr
40 mins
an aneurysm after MI would mostly likely form during what stage
late stage after scar formation
