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Flashcards in Lipoproteins Deck (24)
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Why is it more important to look at LDL than VLDL

LDL has a longer half life, 3-4 days than VLDL which has 3-4 hours


What is the function of LDL and what are the receptors for it

Its receptors are apoB-100 and apoE

Its function is to bind to the LDL to redistribute cholesterol, utilize it and excrete it


What is the function of LRP and what are its ligands


Function is to uptake chylomicron remnants and HDL


What are the ligands for scavenger receptor and what is the function of it

Present on macrophages, uptake of LDL and HDL to form foam cells, it can potentially be a good thing or bad thing, leading or inhibiting atherosclerosis


What is the fate of fatty acids that are consumed in the diet

After hydrolysis and absorption, enterocytes convert them into tri, which are then loaded onto the chylomicrons that take it away in the lacteals.

They can either go the peripheral tissue or liver. In the periphery, LPL converts them into fatty acids and they are absorbed by the muscles and other tissues

In the liver, LRP uptakes these chylomicrons where they can stored or used for energy


What is the fate of cholesterol that enters the body

1. Some of it is excreted immediately

2. What is absorbed goes into the chylomicrons. LPL makes these chylomicrons into chylomicron remnants which can then go to the liver and give away their cholesterol

3. In the liver, bile salts are made from cholestrol and excreted

4. VLDL takes away cholestrol from the liver.

5. HDL can give its cholesterol to VLDL with the help of CETP

6. VLDL become LDL through the help of HTGL and LDL goes on to the peripheral tissues to deposit cholesterol


Why does VLDL has such a short half life

Either less than half of it is taken up by the liver or the other half is converted to LDL via the HTGL enzyme. Afterwards LDL goes to the peripheral tissue to give away its cholesterol


What is the receptor in the liver that takes up HDL



Explain the functions of LCAT and CETP

If HDL wants to sequester free cholesterol it uses the enzyme LCAT to do it whereas if HDL wants to transfer its cholesterol to LDL or VLDL it does this with the help of enzymes CETP


What transporters are important for the transfer of free cholesterol from tissues that have too much cholesterol to HDL

ABC transporters are found in cells and they are responsible for transferring excess cholesterol out of the cells that have too much cholesterol and into HDL


What is the name of the enzyme that converts cholesterol to bile acids

7alpha hydroxylase


Explain the function of ABCG5/ABCG8 and ABCB11

ABCG5/ABCG8 pumps cholesterol out of the liver cells for excretion whereas ABCB11 pumps out bile salts


What is the function of ABCA1 and ABCG1

These transporters are found in the peripheral tissues and they are responsible for pumping out cholesterol from these cells and into the HDL/blood stream or whatever the transporter is.

Tangier disease is associated with a deficiency in ABCA1


What are the exogenous and endogenous lipoprotein extraction pathways

Gut to Chylomicrons to peripheral tissues where they extract the tri using enzyme LPL, this converts chylo to chylo remnants which goes back to the liver and are absorbed via the LPL Related Protein.

VLDL from the liver goes to the peripheral tissue where its contents are extracted by LPL, converting it into IDL which then goes back to the liver and is converted into LDL in the sinusoids by HTGL


What are the 2 transporters important for the sequester of free cholesterol from the peripheral tissues


ABCA1 is important for interacting Apo-A


What are the genes responsible when someone has very high LDLs

1. LDL receptor
2. Apo B-100
3. Apo E


What are the genes responsible when someone has very low HDLs

1. ABCA1
2. Apo A


What are the genes responsible when someone has very high VLDLs/chylo/tri

1. Apo C
3. LPL


What are the genes responsible when someone has very high chylo remnants

1. Apo E


What happens to LDL that is not taken up y the liver

It goes into the vascular intima


Primary high triglyceridemia

It is of 2 types:

1. Can be multifactorial, most common.

2. It can be due to LPL deficiency or Apo C deficiency


Primary hypercholestrolinemia

High cholesterol associated with LDL receptor deficiency or Apo B deficiency


What happens in the disease disbetalipoprotinemia

There is a deficiency in Apo E which causes increased chylomicrons and IDLs.


Tangier disease

ABCA1 transporter deficiency