Atherosclerosis Flashcards
Define arteriosclerosis
The thickening of the walls of arteries and arteriolar usually as a result of hypertension or diabetes mellitus, often associated with loss of elasticity
Problems resulting from arteriosclerosis
Poor tissue perfusion
Inelastic/weak vessels (leading to aneurism)
Increased risk of thrombus formation
Problems resulting from arteriosclerosis
Poor tissue perfusion
Inelastic/weak vessels (leading to aneurism)
Increased risk of thrombus formation
Define atherosclerosis
Accumulation of intracellular and extracellular lipid in the intima and media of large and medium sized arteries
Define atheroma
Necrotic core of the atherosclerotic plaque.
The thickening and hardening of arterial walls as a consequence of atherosclerosis
What are the different theories of atherosclerosis?
Thrombogenic theory (encrustation)
Insudation theory
Monoclonal hypothesis
Reaction to injury hypothesis
describe the Thrombogenic theory of atherosclerosis formation
Plaques for aged by repeated thrombi
Lipid derived from thrombi
Overlying fibrous cap
Inflammation secondary effect
Describe the Insudation theory of atherosclerosis formation
Endothelial injury
Inflammation
Increased permeability to lipid from plasma
Describe the reaction to injury hypothesis for atherosclerosis formation
Plaques form in response to endothelial injury
Hypercholesterolaemia leads to endothelial damage in experimental animals.
Injury increases permeability and allows platelet adhesion.
Monocytes penetrate endothelium.
Smooth muscle cells proliferate and migrate
What are the components of an atherosclerotic plaque?
Cells
Lipid
Extracellular matrix
What are the cellular components of an atherosclerotic plaque?
Endothelial cells
Platelets
Neutrophils
Macrophages
Leucocytes
Smooth muscle cells
What are the components of extracellular matrix?
Collagen
Elastin
Proteoglycans
What are the lipid components of an atherosclerotic plaque?
Intracellular (foam cells)
Extracellular (pools)
What are the stages of atherosclerotic plaque formation?
Intimal xanthoma
Fibrous cap atheroma
Thin fibrous cap -> rupture -> thrombosis
What are the microscopic appearances of atherosclerosis?
Fatty streak: proliferation of smooth muscle cells, accumulation of foam cells, extracellular lipid.
Stable/simple plaque: fibrosis, necrosis, cholesterol clefts, +/- inflammatory cells
Unstable/complicated or vulnerable plaque: disruption of the internal elastic lamina, damage extends into the media, new vessels grow into plaque, plaque fissuring/erode/ulcer etc.
