atherogenesis Flashcards
what is arteriosclerosis
hardening of the arteries - a generic term reflecting arterial wall thickening and loss of elasticity
what are the 3 patterns of arteriosclerosis
arteriolosclerosis; Monckeberg medial sclerosis; atherosclerosis
what is arteriolosclerosis and what can it cause
the hardening of small arteries and arterioles; it can be hyaline (thickening of the vessel wall) or hyperplastic (onion skin thickening of vessel wall); it can cause downstream ischaemic injury
what is monckeberg medial sclerosis
calcific deposits in muscular arteries; may undergo metaplastic change into bone; does not affect the vessel lumen
what is atherosclerosis characterised by?
characterised by intimal lesions (atheromas/atherosclerotic plaques) that protrude into the vessel lumens; plaques made of a rasied lesion with a soft, yellow lipid core covered by a fibrous cap
what can atherosclerosis cause?
plaque can obstruct blood flow; rupture can lead to vessel thrombosis; underlying media is weakened thus increasing risk of aneurysm
major targets of atherosclerosis
large elastic arteries (aorta, carotid); medium sized muscular arteries (coronary, popliteal)
what areas does atherosclerosis most affect
arteries supplying the brain, heart, kidneys, lower extremities
4 major consequences of atherosclerosis
MI; cerebral infarction (stroke); aortic aneurysm; PVD
non modifiable risk factors for atherosclerosis (4)
increasing age; being male; genetic abnormalities; family history
modifiable risk factors for atherosclerosis (5)
hyperlipidemia; hypertension; smoking; T2DM; high CRP levels
what is the contemporary view of artherogenesis
the response to injury hypothesis - endothelial injury leads to chronic inflammatory response, lesions progress due to the interaction of modified lipoproteins, monocyte derived macrophages, and t-lymphocytes with the normal cellular components of the arterial wall
atherosclerosis pathway (7)
- endothelial injury (increased vascular permeability, upreg of adhesion proteins resulting in enhances leukocyte adhesion, thrombosis)
- accumulation of lipoproteins (LDLs + oxidised LDLs are deposited in vessel wall)
- monocyte adhesion to endothelium (migration into the intima, transformation into foam cells)
- platelet adhesion
- factor release (from activated platelets/vessel wall cells, induce smooth muscle recruitment from media or circulating precursors, uptake of modified lipids)
- smooth muscle proliferation (and extra cellular matrix production)
- lipid accumulation (extracellularly and intracellularly, forms a well developed plaque)
examples of chronic endothelial injury (8)
hyperlipidemia; hypertension; smoking; homocysteine; haemodynamic factors; toxins; viruses; immune reactions
why are bifurcations more at risk of atherosclerosis
due to turbulent blood flow (disturbed shear) leading to increased endothelial injury (high EC turnover, poor alignment of EC, inflammatory genes, high permeability, oxidative stress)