MP323 - ATHEROSCLEROSIS Flashcards
atheroma
the accumulation of intracellular and extracellular lipid in the intima of large and medium-sized arteries
atherosclerosis
the thickening and hardening of atrial walls as a consequence of atheroma in large and medium-sized arteries
most common sites of atherosclerosis
- aorta
- coronary arteries
- carotid arteries
- cerebral arteries
- leg arteries
detecting atherosclerosis
ASYMPTOMATIC
- manifests as heart attack or stroke
- low LDL in blood
atheroma - macroscopic features
fatty streak and plaque
elevated zone on arterial wall caused by accumulation of lipid-laden cells
main components of plaque
- lipid-containing macrophages
- extracellular matrix
- cells, proliferating smooth muscle cells
daily cholesterol intake and LDL
normally synthesise around 1000mg/day
daily cholesterol intake around 300mg
2 proteins that carry cholesterol in the blood
LDL (low-density lipoprotein)
HDL (high-density lipoprotein)
how is LDL removed from the blood
LDL RECEPTORS OR SCAVENGER CELLS
- majority LDL receptors located on hepatocytes
- scavenger cells have receptors that bind LDL that has been oxidised or chemically modified
how does oxidised LDL form
- when LDL particles react with free radicals
- increased levels of oxidised LDL when consume a diet high in trans-fat, smoking and poorly absorbed diabetes
consequences of LDL oxidation
- LDL in the endothelial lining of the arteries promotes the accumulation of WBCs (lymphocytes), dendritic cells, and macrophages in the blood vessels
- platelets can stick to areas of inflammation within the arteries, this creates hardened areas inside a blood vessel; plaques
atheroma prevention
- smoking cessation
- diet (reduce fat intake)
- less alcohol
- exercise/weight control
adherent platelets release…
ADP and thromboxane A2
- platelet agonists
- activate more platelets and recruit them to site of vascular injury
aspirin - mechanism of action
blocks production of thromboxane A2 by inhibiting the platelet enzyme (COX-1) for its synthesis
action of aspirin on COX-1 is permanent, lasting for the life of the platelet (7-10 days)
clopidogrel - mechanism of action
irreversible inhibitor of ADP receptor on platelets (P2Y12 receptors) and so prevents ADP from activating platelets
