Atherosclerosis and lipometabolism Flashcards
(56 cards)
How do HDLs and LDLs compare in terms of structures?
The components are very similar but the apoprotein is quite different and this is the factor that gives the major properties
How are dietary triglycerides and cholesterol metabolised?
They are broken down and packaged into chylomicrons
Chylomicrons are then broken down into smaller and smaller lipids and into chylomicron remnants- these products can end up in the adipose tissue and blood vessels
Where do most circulating lipids come from?
They are endogenous
Where does a small proportion of lipids end up?
In the walls of blood vessels
What are chylomicron remnants very good at?
Getting into the blood vessel wall- into the tunica intima
They’re very important in the process of atherosclerosis
What is atherosclerosis?
An inflammatory fibre-proliferative disorder
What is the first stage of atherosclerosis development?
LDLs get into the endothelium
What happens once LDLs get into the endothelium?
You get release of growth factors and cytokines which attract inflammatory cells such as monocytes
Formation of foam cells in the endothelium
Proliferation of fibroblasts and smooth muscle cells- expands the plaque
What are foam cells?
Macrophages that contain a lot of lipid
What changes occur that characterise endothelial dysfunction that precede lesion formation?
Greater permeability of endothelium
Up-regulation of leucocytes and endothelial adhesion molecules
Migration of leucocytes into the artery wall
What does the endothelium normally do?
It is an active line of cells that makes growth factors and inflammatory mediators etc
What is the earliest recognisable lesion of atherosclerosis?
The fatty streak
What causes the fatty streak?
Aggregation of lipid-rich foam cells (derived from macrophages and T lymphocytes within the tunica intima)
What do the lesions include later on after the fatty streak?
Smooth muscle cells
In what way are fatty streaks usually formed?
In the direction of blood flow
What causes the formation of a complicated atherosclerotic plaque?
Death and rupture of foam cells in the fatty streak- formation of a necrotic core
What causes formation of the fibrous cap in a complicated atherosclerotic plaque?
Migration of smooth muscle cells into the intimate and laying down collagen fibres results in the formation of a protective fibrous cap over the lipid core
Why is the fibrous cap extremely important?
It separates the highly thrombogenic lipid-rich core from circulating platelets and coagulation factors
What are stable atherosclerotic plaques characterised by?
A necrotic lipid core covered by a thick vascular smooth muscle-rich fibrous plaque
What happens when an atherosclerotic plaque becomes unstable?
The plaque ruptures and exposes the thrombogenic lipid rich core to the circulating platelets and coagulation factors which leads to thrombosis
What else can plaque erosion cause?
Hardening of the arteries which results in weakening and thinning of vessel wall leading to aneurysm and possible haemorrhage
What do complicated atherosclerotic lesions often contain?
Calcium
How can coronary artery disease be detected?
By doing a CT scan of the heart- detects any calcium
What characterises a vulnerable plaque?
Thin fibrous caps
Core rich in lipid and macrophages
Less evidence of smooth muscle proliferation
