Dyslipidaemia Flashcards
In basics what is Dyslipidaemia?
Elevated blood cholesterol, TAG, or both
What is hypercholesterolaemia?
Elevated blood cholesterol
What is hypertriglycerideaemia?
Elevated blood TAG
what is hyperlipoproteinaemia
Elevated blood lipoproteins
What is hyperchlomicronaemia?
elevated blood chylomicrons
what is the ideal total cholesterol level in your blood?
<5.2
what is the ideal LDL level in your blood?
<1.8
what is the ideal HDL level in your blood?
> 1.6
what should TC:HDL be?
<4
what does PPL mean?
post prandial lipaemia - fat in the blood after a meal
what is the leading cause of mortality and morbidity?
CVD
what is a lipid? (2)
organic molecules, poorly soluble in water
How many oxygen atoms does cholesterol have?
1
What is a triglyceride made of?
3 cholesterol molecules
why do we need fat? (5)
- energy
- protection of organs
- thermal insulation
- neural insulation
- vitamins (A, D, E & K)
why do we need cholesterol in the cell membrane?
give stroll rigidity
What is cholesterols relationship with water?
Cholesterol is very hydrophobic
How is cholesterol and TAG carried around the body?
Inside a lipoprotein
what is the name of the process where vegans make their own cholesterol?
denovosynthesis
what do bile acids do?
they help break down cholesterol, some will get excreted and some will get recycled
where can TAG be stored and for what purpose?
in the liver for energy
what are the 4 main lipoproteins?
- Chylomicron
- VLDL
- LDL
- HDL
what is a APO protein?
a ‘badge’
how much TAG does chylomicron contain?
90%
how much TAG does VLDL contain?
65%
where does chylomicron transport TG to and from?
ships the TAG to the liver or the tissue
where does VLDL transport TAG to and from?
ships TAG from the liver to the tissue
where does HDL transport TAG to and from?
from the tissue back to the liver
why can’t LCFA get into the blood?
they are hydrophobic
how does LCFA and cholesterol get into the blood?
LCFA go through a special receptor in the epithelial cells and we repackage them into TAG in the epithelial cells
the the cholesterol get repackaged as a cholesterol ester
then they both get packaged into the chylomicron which goes into the lymph. This then drains into the blood stream via the left subclavian vein (collar bone)
what Apo proteins does HDL donate to chylomicron?
Apo 2 and Apo E
what is the half life of LDL?
1-2 days
how long does it take for chylomicrons to disappear
1-2 hours
what can cause oxidative stress?
smoking, having high blood glucose
what does oxidative stress lead to?
free radicals
why is there a problem when a macrophage engulfs a free radical?
the macrophage has no internal feedback for how much cholesterol it has - so cannot recognise when it has too much cholesterol
why is LDL considered to be “bad” cholesterol?
it gets consumed by a macrophage which then forms a foam cell under the
endothelium.
what are the 6 stages of atherosclerosis?
- foam cells
- fatty streak
- Intermediate lesions
- atheroma
- fibrous plaque
- complicated lesions rupture thrombosis occlusion
what organ does a chlymicron come from?
Intestine
what is the relationship between an LDL and a VLDL?
An LDL is an old VLDL that doesnt have any tiglycerides
anymore thus share the same B100 protein
what are the different HDL’s dependent on and where is it made?
Their density. Made in the intestine or the liver
what is the extra Apo protein HDL has?
Apo A
how does the body get cholesterol back to the liver?
Any cell with too much cholesterol expresses scavenger receptor B
allowing Apo A to doc and it will ship the cholesterol to the liver.
2 drugs which can be used for Dislipidaemia
statins and resins
how do statins work?
a statin stops the HMG-CoA reductase so the liver is unable to produce it’s own cholesterol. Thus up regulating the LDL receptors, taking more cholesterol out of the blood system
what does stating to to bile?
A statin prevents the recycling of bile so you lose more cholesterol from your system
how do resins treat dyslipidaemia?
prevents the recyling of bile acids to the cell expresses more LDL aswell
How does Ezetimibe treat dyslipidaemia?
prevents cholesterol getting into your system in the first place - knocks out cholesterol transport protein in the intestine
how does a high fat diet affect the chylomicrons in your body?
the amount of chylomicrons have increased in size carrying fat. There is an exchange of TAG with existing LDL, some cholesterol gets exchanged for TAG via ester transferase enzyme.
the chylomicron takes more cholesterol from the LDL and gives less fat to the LDL to the chylomicron enlarges and deliver TAG to the liver, where it becomes a chylomicron remenant as it has more cholesterol in it
what does having a lot of TAG rich chylomicrons cause?
oxidative stress - which stops the endothelium from working properly so things can get through it and settle in the endothelium wall
what enzyme helps LDL deliver TAG?
hepatic lipase
what happens to our LDL remnant in the blood stream?
it gets oxidised and becomes damaged LDL so a macrophage is more likely to consume the oxidised LDL forming a foam cell.
what does HDL do we the elevated number of chylomicrons in the blood?
HDL reacts with the elevated level of chylomicrons in the system and swaps cholesterol from TAG and delivers the TAG to the liver and becomes a HDL remnant.
A HDL remnant is more rapidly removed from circulation, if you get rid of HDL remnants what happens to the chylomicrons?
the HDL levls in your blood goes down so you lose the ability to give chylomicrons the Apo C2 and E they need to get out the system, so the chylomicron levels increase.
What results from the rapid removal of HDL?
TAG is unable to get out of the system causing oxidative stress
what is flow mediated dilation?
An assessment of endothelial function
How does reduced fat intake help dislipidaemia?
lowers chylomicron concentrations
How does reduced saturated fat intake help dislipidaemia?
sat fat reduces LDL clearance and increases hepatic C production
How does increasing fibre content help dislipidaemia?
increases cholesterol loss through the gut
how does limiting sugar consumption help dislipidaemia?
prevents insulin resistance
How does reducing alcohol help dislipidaemia?
80 % of alcohol is metabolised by the liver and up to 31% of an alcohol bolus ends up as VLDL
why do limiting fructose consumption help dislipidaemia?
avoids hepatic TAG output
How can antioxidants help dislipidaemia?
they can protect against free radical damage
how does exercise help dislipidaemia?
increases delivery and use of TAG during exercise thus reducing the blood TAG pool. You also increase HDL so you have a greater lending library of APO A and Apo C2 to get rid of the chylomicrons quicker
How does exercise enhance TAG clearance?
increases LPLase expression and activity
how does exercise improve endothelial function?
Prevents infiltration of lipoproteins/macrophages into the sub endothelial space
what form of affect does exercise take on dyslipidaemia?
repeated, acute effects
