Lipid metabolism and control of blood lipids Flashcards
What are some physiological functions of lipids
energy source insulation organ protection steroid hormone synthesis membrane structure and function
What is a triglyceride
3 molecules of palmitic acid
Where are triglycerides stored
White adipose tissue
What are phospholipids comprised of
hydrophilic head and 2 hydrophobic tails
What are shingolipids
membrane lipids with 1 fatty acid tail
What happens when cholesterol reaches its max level
it switches itself off
What is lecithin cholesterol alkyl transferase and its role
An enzymes
converts cholesterol in to cholesteryl ester
3 sources of fatty acids
Dietary fatty acids
adipose tissue
Endogenously synthesised fatty acids
What happens to fatty acids
emulsified by bile
degradation by lipases
absorption and conversion into triglycerols
incorporation in to chylimicrons
What are lipoproteins
Molecular complexes that consist of lipids and proteins
What is the function of lipoproteins
The transport of vesicles for lipids in blood plasma deliver the lipid components to various tissues for utilisation
What is the realtionhip between the density and the size of the lipoprotein
as lipoprotein increases
size decreases
What is an apolipoprotein
The protein before the lipid has joined
What are the functions of apolipoproteins
Structural component of lipoproteins
enable transport of lipid
interact with cell surface receptors
activate/inhibit enzymes involves in lipoprotein metabolism
What are the three main pathways that are responsible for generation and transport of lipids
Exogenous pathway
endogenous pathway
reverse cholesterol transport
explain the 5 steps of the exogenous pathway
1-chylomicrons bind dietary triacylglycerols
and cholesterol in the intestines
2-transported in blood to adipose and muscle
3- lipoprotein lipase on surface of capilllary act of chylomicron and release free fatty acids and remnants of chylomicron remain
4- remnant taken up by LDL receptor at liver
5- enters inestine in the form of cholesterol and bile acids
Explain the 6 steps of endogenous pathways
- Manufacture of lipids in body itself
- dietary cholesterol in liver is packaged in VLDL ( very low density lipoprotein)
- lipoproteinlipase will release free fatty acid from VLDL to give IDL (intermediate density lipoprotein)
- 1/2 of IDL is taken up by the liver (by hepatic lipase) and 1/2 forms LDL
- LDL delivers cholesterol to peripheral tisses
- HDL removes cholesterol from peripheral tissue - reverse cholesterol transport
What does lipoprotein lipase do
Acts on lipoproteins to release FA and monoacylglycerol
What does monoacylglycerol thus do
Releases further FA and glycerol
What happens when FA enter the mitochondria
Through the carnite cycle
undergo beta - oxidation
acetyl - CoA formed
What happens to glycerol from adipose tissue
it is phosphorylated into glycerol-3-phosphate
enters the glycolytic pathway
acetyl CoA formed
What happens to medium chain fatty acids
enter and undergo beta-oxidation
What happens to long chain fatty acids
Long chain fatty acids need to go through the carnite cycle
What happens when actyl coa is in XS
ketones are produced
What is dyslipidemia
Higher/lower than normal conc of lipoproteins in plasma specifically
What happens to total cholesterol levels during dyslipiemia
Increase
What happens to LDL when dyslipidemia occurs
Decreases
What happens to TG when dyslipidemia occurs
Increases
What happens to HDL when dyslipidaemia occurs
Decreases
