Adipose/Muscle:
VLDL is transported to muscle in the
blood from the liver.
It loses free fatty acids to become LDL.
Intestine: By lipoprotein lipase.
These free fatty acids are stored and used
in the muscle.
LDL returns to the liver and binds to LDL
receptors.
To synthesise cholesterol.
HDL:
Picks up cholesterol from tissues.
Can deliver this cholesterol to other
lipoproteins that need it e.g IDL
:
95% of dietary lipids are triglycerides.
The rest: cholesterol, free fatty acids and
, phospholipids.
TG is digested in the duodenum into
monoglycerides and free fatty acids. Cholesterol synthesis:
By gastric lipase.
These free fatty acids are absorbed into
the endothelial cell in the intestine.
They are then packaged into triglycerides
again by the smooth endoplasmic
reticulum.
Then packaged into chylomicrons by the
Golgi apparatus.
Enterocytes:
Free fatty acids combine into
triglycerides. HMG CoA reductase converts HMG CoA
And packed with cholesterol to form to mevalonic acid.
chylomicrons. This then is synthesised to cholesterol.
Chylomicrons: transports TGs and In the hepatocyte
cholesterol HMG CoA reductase is what statins work
Adipose/muscle: on
The chylomicron activates the endothelial
lipoprotein lipase (LPL) Endocytosis of LDL:
This converts chylomicron to fatty acids LDL receptors found on hepatocytes.
and glycerol. LDL will bind to these receptors.
These are taken up by the tissue for The membrane will close around it.
energy and storage. LDL is broken down to release cholesterol
Cholesterol-rich chylomicron remnants and amino acids.
then circulate back to the liver where
they are cleared.
Summary:
Dietary lipids absorbed in the small
intestine as free fatty acids and
monoglycerides.
In the circulation, these are converted to
triglycerides and then into chylomicrons.
This chylomicron activates LDL which
then causes fatty acids and glycerol to be
taken up by the tissue.
The left-over contents in the chylomicron
remnant returns to the liver (rich in
cholesterol)
VLDL LDL IDL HDL
20-30nm Contains
30-80nm Contains apoB- apoA1 and
Present at low
Contains apoB- 100. apoA2.
concentrations
100. Low 7-20nm
.
Large triglyceride diameter
TG conc in
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