9. Atherosclerosis Flashcards
What is the definition of atherosclerosis?
Accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries
What is the fatty streak in atherosclerosis and how does it appear?
Lipid deposits in the intima.
Yellow and slightly raised
What is a plaque in atherosclerosis and how does it appear both to the eye and microscopically?
Fatty streak grows to form plaque. Raised and white to yellow in colour, impinge on lumen of artery.
Fibrosis, cholesterol clefts, disruption of internal elastic lamina and extension into the media.
What is the definition of arteriosclerosis?
Thickening of the walls of arteries and arterioles usually as a result of hypertension or diabetes mellitus.
What happens when a plaque leads to haemorrhage?
New vessel that has developed within the plaque haemorrhages, expanding the plaque, leading to vessel occlusion or breaking open of the plaque.
What happens in thrombus formation on a plaque?
Usually on an ulcerated plaque, where the fibrous cap is eroded from underneath and the core of the plaque is exposed to the blood which i high thrombogenic. The thrombus may occlude the vessel.
What happens in aneurysm formation from a plaque?
Elastic tissue within the arterial wall is destroyed by the plaque, weakening the wall, leading to local dilatation, and possible vessel rupture.
What can be seen, especially in cerebral arteries, when a patient has hypertension in addition to atherosclerosis?
Rupture of the atherosclerotic artery
Name 3 common sites of atherosclerosis
Aorta (abdominal) Coronary arteries Carotid arteries Cerebral arteries Leg arteries
What are the three basic components of atherosclerotic plaque?
Cells - eg macrophages, leukocytes, smooth muscle cells.
Intra and extracellular lipid.
Extracellular matrix - eg collagen, elastin, proteoglycans.
What result in endothelial dysfunction as proposed initiating factors for plaque formation in atherosclerosis?
Hyperlipidaemia, hypertension, smoking, haemodynamic factors.
What happens in fatty streak formation?
Lipid droplets (LDLs) and monocytes cross endothelium, accumulate in intima. Become oxidised and macrophages ingest lipid, forming foam cells. Cause endothelium to bulge, smooth muscle cells migrate to lesion from media, proliferate.
Once a fatty streak has formed, what happens in its maturation into a plaque?
Grows as number of foam cells and smooth muscle cells increases, some smooth muscle cells take up lipid, appear foamy, and some lie over plaque but underneath endothelium, forming roof, reinforced by collagen, elastic, matrix proteins, forming fibrous cap. Endothelium stretched, gaps appear between endothelial cells, platelets adhere to gaps. Cells in centre plaque die, necrosis, dead cells release cholesterol, crystals appear, small blood vessels grow in plaque from adventitia and plaque may undergo calcification.
What are cholesterol clefts?
Linear holes in a tissue section left behind when cholesterol crystals are removed from a plaque.
What 3 diseases does arteriosclerosis include?
Atherosclerosis
Atheriolosclerosis
Monkeberg’s disease
