Angina and Acute Coronary Syndromes Flashcards
what is the purpose of lipoproteins?
to transport lipids in plasma
what are lipoproteins composed of?
Lipids (triglyceride or cholesterol esters)
phospholipids
cholesterol
proteins
in what form are dietary cholesterol and fats taken up into the blood stream?
chylomicrons
What happens to fats/cholesterol in the peripheral tissues?
they are broken down into fatty acids (which are taken up by tissues) and glycerol by lipoprotein lipase
the chylomicron remnants are then taken up by the liver and the cholesterol they contain is added to the cholesterol that the liver has synthesised
the liver then secretes cholesterol and newly formed triglycerides in the form of VLDL
how is VLDL converted into LDL?
by the absorption of fatty acids in the peripheral tissues
how do HDLs arise?
from the recycling of cholesterol (cell breakdown) in peripheral tissues
How are bile acids formed?
from the oxidation of cholesterol
what happens to bile acids?
they are secreted into the GI tract, mixed with cholesterol
what do bile acids do?
emulsify fats
what happens to bile after use?
it’s returned to the liver via the portal vein
what do LDL and VLDL do in the plasma? (why are they bad?)
involved in the formation of fatty streaks
inhibit fibrinolysis (fibrin breakdown)
activate platelets- which increases the risk of atherosclerosis
What do HDLs do in the plasma? (why are they good?)
increase fibrinolysis
decrease aggregation
reduces the risk of atherosclerosis
what are Hyperlipidaemias?
elevated LDL/VLDL/cholesterol levels
what are the 2 main methods for controlling hyperlipidaemias?
lifestyle changes
lipid- lowering drugs
Give three lifestyle changes to treat Hyperlipidaemias
- reduce sat fats
- increase unsat fats
- increase fibre
- avoid trans fats
- avoid hydrogenated fats
- increase exercise
what do lipid-lowering drugs do?
reduce LDL and raise HDL levels
what drugs tend to be given to treat hyperlipidaemia? (2)
Statins and Ezetimibe
what sort of genetic defect can cause hyperlipidaemia? (2)
defect in the LDL receptor or ApoB protein
What sort of mutation is that that causes hyperlipidaemia?
Autosomal dominant
what proportion of the UK population are heterozygous for familial hyperlipidaemia?
1:500
How does being heterozygous for familial hyperlipidaemia affect the individual?
tends to develop CVD by the age of 40-50 years
What proportion of the UK population are homozygous for familial hyperlipidaemia?
1:1000000
How does being homozygous for familial hyperlipidaemia affect the individual?
tends to develop severe CVD in childhood
How is familial hyperlipidaemia primarily treated?
statins
give an example of a widely used statin
Atorvostatin
what do statins do?
competitively inhibit HMGCoA reductase (the rate limiting enzyme in production of cholesterol (similar structure to cholesterol)
reduces liver prouduction of cholesterol leading to more LDL receptors, therefore increased removal of LDL from plasma
increases HDL and lowers triglycerides
how is cholesterol produced?
when HMGCoA allows AcetylcoA to be converted to mevalonate.
Mevalonate then is converted to Cholesterol
give side effects of statins (4)
- Myositis (muscle inflammation)
- rhabdomyolysis (muscle breakdown)
- altered liver function
- altered kidney function
why are statins controversial?
many statins are prescribed and used when lifestyle changes could be made (which would be more effective and safer)
what 4 other drug classes can be used to lower cholesterol?
Anion exchange resins
Fibrates
Nicotinic acid
Fish oils
what do anion exchange resins do?
sequester bile acids in gut
what do fibrates do?
they are agonists are PPARa receptor
What do Nicotinic acids (vitamin B3) do?
reduce cholesterol, however mechanism not well understood
What do fish oils do?
fish are rich in omega 3 fatty acids which are linked with a decreased CVD risk by reducing platelet aggregation and decreasing fibrinogen
little evidence supporting fish oils as a treatment
reduce plasma lipids but increase cholesterol
define angina
chest pain caused by reduced blood flow, therefore reduced oxygen supply to the heart. (an imbalance in supply and demand of oxygen in the heart)
what are the 2 types of angina?
stable and Acute Coronary Syndrome (ACS)
what is stable angina also known as?
Angina of effort
which is the most common form of angina?
stable
what is the primary cause of stable angina?
atherosclerosis of the coronary artery
what triggers stable angina pains? (3)
exercise, excitement, cold weather
How is stable angina released?
rest