Atherosclerosis, Lipoproteins and Lipid-Lowering Agents Flashcards
What is the main difference in the composition of LDLs and HDLs?
They have different apoproteins
What are dietary triglycerides and cholesterol packaged into once they are absorbed?
Chylomicrons
What are chylomicrons broken down into?
Chylomicron remnants
Are most circulating lipids endogenous or exogenous?
Endogenous
What is the significance of chylomicron remnants with regards to atherosclerosis?
They are very good at getting into the tunica intima
Define atherosclerosis.
Atherosclerosis is an inflammatory fibro-proliferative disorder
What cells are recruited in the process of atherosclerosis?
Macrophages (which turn into foam cells)
Fibroblasts
Smooth muscle cells
What must initially happen for the process of atherosclerosis to begin?
Increase in permeability of the endothelium
Upregulation of leukocytes and cell adhesion molecules
Migration of leukocytes into arterial wall
What can happen as the atheroma grows larger?
Some of the foam cells die and rupture, releasing their toxic contents to form a lipid necrotic core
Which cells are responsible for producing a protective fibrous cap over the fat core?
Smooth muscle cells lay down collagen fibres
What is an unstable atherosclerotic plaque?
The fibrous cap thins and eventually ruptures, exposing the thrombogenic lipid core to the platelets and coagulation factors
This causes THROMBOSIS
NOTE: plaque erosion is also associated with hardening of the arteries, leading to weakening and thickening of the vessel wall leading to aneurysm and possible haemorrhage
What do complicated lesions often contain?
Calcium
What are some characteristics of vulnerable plaques?
Thin fibrous cap
A core rich in lipid and macrophages
Less evidence of smooth muscle proliferation
What can modify LDL cholesterol?
Low HDL
Diabetes
Smoking
Hypertension
What do low HDL cholesterol levels tend to be associated with?
High triglyceride levels