atherosclerosis, lipoproteins and lipid lowering drugs Flashcards
How do the structures of HDL and LDL differ?
- apoprotein
What is the pathway of lipid metabolism?
dietary triglycerides and cholesterol are broken down and packages into chylomicrons
this is broken down further into chylomicron remnants which then end up in the adipose tissue and blood vessels
What process are chylomicron remnants very important in?
-atherosclerosis
they are very good at getting into the blood vessel wall - tunica intima
What is the definition of atherosclerosis?
it is an inflammatory fibro-proliferative disorder
Summarise the stages of atherosclerosis
- LDL get into the endothelium
- there is a release of growth factors and cytokines, which attract monocytes
- formation of foam cells in the endothelium
- proliferation of fibroblasts and smooth muscle cells, which expand the plaque
At what stage does endothelial dysfunction occur at in atherosclerosis?
- early stages
- precede lesion formation
What happens to the artery wall during endothelial dysfunction?
- greater permeability of the endothelium
- up-regulation of leucocytes
- endothelial adhesion molecules
- migration of leucocytes
What does a fatty streak signify?
- it is the earliest recognisable lesion of atherosclerosis
What causes fatty streaks?
- aggregation of lipid-rich foam cells
- later on the lesion will also include smooth muscle cells
- the fatty streaks are usually formed in the direction of blood flow
How does an atherosclerotic plaque come about?
- death and rupture of the foam cells in the fatty streak
You get formation of a necrotic core. The migration of smooth muscle cells into the intima and laying down collagen fibres results in the formation of a protective fibrous cap over the lipid core
What are stable atherosclerotic plaques characterised by?
- a necrotic lipid core covered by a thick vascular smooth muscle-rich fibrous plaque
What happens with an unstable atherosclerotic plaque?
the plaque ruptures and exposes the thrombogenic lipid rich core to the circulating platelets and coagulation factors
this leads to THROMBOSIS
What other complication can plaque erosion lead to?
hardening of the arteries, can lead to possible aneurysm or haemorrhage
What key thing does CT scans look for with atherosclerotic lesions?
-calcium
it is believed the more calcium the more symptomatic you will be
What type of cholesterol is strongly associated with atherosclerosis and CHD events?
LDL
modified by other risk factors such as low HDL cholesterol, smoking, diabetes, hypertension
