Atherosclerosis and Heart Disease Flashcards
Atherosclerosis characterization
characterized by raised fibrofatty plaques in intimal lining of medium and large-sized blood vessels
atheromas
fatty material that builds up inside arteries
what does atheromas consist of?
foam cells, proliferating smooth muscle cells, extracellular lipids, fibrous tissue
atherosclerosis symptoms
process is usually asymptomatic until vessel is approximately 75% occluded
- at this time, heart can show signs of ischemia (eg. angina) particulary during times of physical exertion
lipid metabolism pathway
- chylomicron
- lymph
- subclavian veins => chylomicron circulates in blood
- adipose tissues => release triglycerides for storage
- liver => absorbed and broken down -> triglycerides, cholesterol, vitamins
what is liver responsible for
producing cholesterol for cells of the body
chylomicron
lipids absorbed from GI tract bound to a lipoprotein
how can lipids be metabolized
have to be transported by being bound to lipoprotein
since lipids CANNOT be readily dissolved in blood plasma
types of lipoprotein
- VLDL
- LDL
- HDL
cholesterol pathway
- VLDL (synthesized cholesterol and cholesterol from chylomicron)
- adipose tissue - release triglycerides for storage
- VLDL -> LDL
what does LDL do once converted from VLDL
circulate around body and deliver cholesterol to tissues
or
taken up by liver and recycled
what occasionally happens to LDL
can get consumed by macrophages
- plays a role in development of atherosclerosis
HDL
high-density-lipoprotein
- produced in liver
- released into blood and is reponsible for picking up access cholesterol from tissues and plays a scavenger role
what does HDL do to cholesterol
“drops-off” cholesterol at liver and is returned to circulation
what happens in cholesterol removed by HDL?
excreted from body in bile
Atherogenesis
“Response to Injury Theory”
- mechanism of atherosclerosis development believed to begin w/ endothelial damage and inflammation
two types of how intima of artery can be damaged
mechanical stress
oxidative stress
mechanical stress
ie. shear stress
- ↑BP or ↑blood viscosity
oxidative stress
certain metabolic processes result in generation of high levels of ROS
eg. ↑LDL, diabetes, smoking
ROS
reactive oxygen species
- can damage lipids, proteins, DNA, intima or coronary arteries
what does damage to endothelium induce
induces an inflammatory response
activates adhesion molecules, growth factors and ↑angiotensin II, ACE levels
what does inflammation in atherogenesis result
accumulation of macrophages
what does macrophages do in inflammation
consumes LDL and become foam cells that forms initial fatty streak
foam cells
type of macrophage that localize to fatty deposits on blood vessel walls
angiotensin II in atherogenesis
=> vasoconstriction (vasospasm) and ↓NO levels
what does vasoconstriction and ↓NO levels r/t angiotensin II cause?
vascular smooth muscle proliferation
enhanced inflammation
vasoconstriction
promotion of thrombosis
what does angiotensin II in atherogenesis promote
cardiac cell growth and contributes to cardiac hypertrophy
thrombi easily forms where
lesions
what happens to lesions as it grows?
- occludes lumen of vessel
- may form a thrombus => complete occlusion quickly
- weakens blood vessel wall => ↓activity
- may calcify => further rigidity of blood vessel wall
as lesions grow what can it lead to?
aneurysms, rupture or hemorrhage in wall
stability of plaques is affected by what?
amount of lipid in plaque
stability of plaque w/ lots of lipid
very unstable, progress quickly and attract more macrophages and platelets
stability of plaque w/ more fibrous tissue and little lipid
more stable and less likely to rupture => ↓predisposition to thrombosis
