Topic 1: Cholesterol Flashcards
Cholesterol is a _____, so made of __,__ and__.
lipid
C H O
Cholesterol is use to make _____ _________ - it regulates ________
cell membranes
fluidity
Cholesterol is obtained from the _____ and can be made in the ______.
diet
liver
Cholesterol is _________ in water, so is carried in the blood combined with _______ ___________ (LDL or HDL)
insoluble
soluble lipoproteins
LDL cholesterol binds to _____ _________ on cell membranes and enters cells to be used in membranes.
LDL receptors (LDLR)
What would be the (2) medical advice to reduce cholesterol? (2 points)
- eat less saturated fat and cholesterol in diet, more fibre, plant sterols/stanols
- drug treatment – take STATINS
What are the (4) functions of cholesterol in the body?
- Regulates fluidity of cell membranes
- Used to make vitamin D
- Used to make steroids
- Used to make bile salts (for lipid digestion)
Why is it a problem to have too much cholesterol?
3 points
- Too much cholesterol in the body can lead to high blood cholesterol
- There is a correlation between high blood cholesterol and incidence of CVD
- You may be at risk of developing CVD if your blood cholesterol level is greater than 5.2mmol/litre
Too much cholesterol in the body can lead to ____ _______ ____________.
There is a correlation between high blood cholesterol and incidence of CVD
high blood cholesterol
Cholesterol is ________ in water because it has many _______ bonds which are _____-________.
Therefore it cannot _______ _____with water.
insoluble
C-H
non-polar
hydrogen bond
Cholesterol must combine with __________ to be transported in the bloodstream.
lipoproteins
Lipoproteins contain polar __-__ groups on their surface, so they can form _______ ______with water molecules.
N-H
hydrogen bonds
Name the 2 main types of LIPOPROTEINS which combine with and transport cholesterol. (2 points)
- High-density lipoprotein (HDL)
2. Low-density lipoprotein (LDL)
How do you calculate total cholesterol? (give the formula)
Total cholesterol = HDL cholesterol + LDL cholesterol
How do you calculate cholesterol ratio?
total cholesterol number / HDL cholesterol number
State the optimal cholesterol ratio? (1 point)
- less than 3.5 to 1.0
the higher the ratio, the higher the risk of heart disease
The RATIO of HDL to LDL is considered to be important when assessing the risk of developing CVD.
The more HDL, the ______ the risk of developing CVD.
lower
Cholesterol in the _____ (from diet or made in the _____) needs to be taken up by _____, to be used by cells to make _____ _________.
Tissue cells have ____ __________ (specific for binding to LDLs) on their cell membranes.
blood
liver
tissues
cell membrane
LDL receptors
LDLs carry cholesterol in blood from _______ to _______.
At the _______, LDL’s binds to _____ _________ on cell membrane + {LDL/cholesterol} are taken up by cells by __________.
liver
tissues
tissues
LDL receptors
endocytosis
Too much cholesterol and ________ fat in diet leads to too much ___ ________ in blood which overloads ____ ___________ (tissues cannot take up any more ____ ________), resulting in high blood cholesterol levels.
__________ fats may also decrease ____ _________ activity so this further increases _______ _________ levels.
saturated
LDL cholesterol
LDL receptors
LDL cholesterol
saturated
LDL receptor
blood cholesterol
If excess cholesterol circulates in the bloodstream – why might this put someone at higher risk of developing CVD?
(11 steps)
(Atherosclerosis)
- endothelium of artery walls may become damaged
- inflammatory response
- cholesterol accumulates in artery walls
- causing an atheroma
- calcium salts and fibrous tissue form a plaque
- narrowing the artery lumen
- loss of elasticity of artery wall - atherosclerosis
- increasing the risk of a plaque or blood clot blocking the artery
- reduced blood flow and oxygen to (heart muscle/brain) tissue
- death of (heart/brain) cells
- increased risk of CVD – heart attack or stroke
Key Summary: How does {saturated fat/cholesterol} in the diet cause high blood cholesterol?
(4 steps)
- High saturated fat from diet IS USED TO MAKE CHOLESTEROL IN THE LIVER, FORMS LDLs AND REDUCES THE ACTIVITY OF LDL RECEPTORS ON CELLS
- LDLs TRANSPORT CHOLESTEROL FROM LIVER TO TISSUES
- If the concentration of LDL CHOLESTEROL IN BLOOD IS TOO HIGH, LDL receptors on cells of tissues are OVERLOADED, so all of the cholesterol can’t be taken up by cells to be used (eg. for cell membranes)
- Therefore more LDL cholesterol remains in the blood and results in HIGH BLOOD LDL CHOLESTEROL
Key Summary: What is the evidence for a causal relationship between blood cholesterol levels and CVD? (6 steps)
- High BLOOD LDL CHOLESTEROL, may increase risk of atheroma/plaque formation (if artery endothelium is damaged)
- Artery lumen narrows and loss of elasticity of artery wall - atherosclerosis
- Increased risk of blood clot blocking coronary arteries (or arteries to brain)
- Reduced blood flow and oxygen to heart muscle tissue (or brain tissue)
- Cell {damage/death}
- INCREASED RISK OF HEART ATTACK (or stroke)
Describe the {lifestyle/diet} - to increase HDL and decrease LDL (4 points)
- Reduce saturated fat in diet
- Reduce cholesterol in diet
- Increase fibre in diet
- Increase foods which contain plant sterols or stanols (nuts, vegetable oils, cereals, seeds, fruit and vegetables)
Name the CVD medication drug? (1 point)
What does it do? (1 point)
- Statin
1. lower blood cholesterol
What are the (4) benefits of HDLs?
NOTE: HDLs contain a higher proportion of protein (hence higher density)
- Transport cholesterol FROM BODY TISSUES TO THE LIVER where it is BROKEN DOWN
- So higher HDLs helps to LOWERBLOOD CHOLESTEROL LEVELS
- May also help remove lipid from atherosclerotic plaques
- Can reduce CVD risk
How do statins work? (1 point)
- Inhibit an enzyme involved in cholesterol synthesis
What is the benefit of statins? (1 point)
- Reduce blood cholesterol
What are the (4) {risks/side effects} of statins?
- Muscle inflammation
- Muscle pain
- Liver damage
- Nausea
What are the non-controllable factors that lead to high blood cholesterol? (3 non-controllable factors)
- Genetic predisposition
- Age
- Gender
How can genetic predisposition lead to high cholesterol? (2 points)
- Familial hypercholesterolemia (FH) - inherited condition caused by an mutated allele, which leads to faulty LDL receptors which cannot take up cholesterol into cells
- so cholesterol levels are higher than normal from birth
How can age lead to high cholesterol? (1 point)
- Cholesterol increases in most people as they get older, as their body produces more cholesterol
How can gender lead to high cholesterol? (1 point)
- Before menopause, women tend to have lower total cholesterol than men. After menopause, though, women’s LDL levels tend to increase.
How does a high fibre diet reduces the risk of CVD? (1 point)
- Soluble fibre has been shown to lower blood cholesterol levels by binding to bile (composed of cholesterol) and taking it out of the body.
