Lipid Mobilization/Transport Flashcards
What is a lacteal?
Lymphatic vessel of the small intestine that absorbs digested fats and packages them into chylomicrons.
In the digestive system, which two secretions ensures the proper digestion of fats?
- bile: emulsifies fats into micelles
- pancreatic lipase: breaks down triglycerides (fats) into free fatty acids and glycerol
What is the function of a lipoprotein?
Transports lipids through the blood.
What are the five types of lipoproteins found in the body?
- chylomicrons
- VLDL (very low density)
- IDL (intermediate-density)
- LDL (low-density)
- HDL (high-density)
Which lipoprotein is the only one that transports cholesterol back to the liver?
HDL
What is the function of LDL? HDL?
LDL: transports cholesterol to tissues
HDL: transports excess cholesterol to the liver for excretion
Both chylomicrons and VLDL function in the transport of triglycerides to tissues, but differ in the location of their synthesis. Where are they synthesized?
Chylomicrons: small intestine
VLDL: liver
[Mnemonic]
HDL: healthy cholesterol
LDL: lousy cholesterol
(how to distinguish between HDL and LDL)
HDL: healthy cholesterol
“GOOD”
LDL: lousy cholesterol
“BAD”
For lipid transport, IDL is the transition state between VLDL and LDL. What are the two fates of IDL?
- converted into LDL
- reabsorbed by the liver
During fatty acid mobilization, what is the function of lipoprotein lipase? Hormone-sensitive lipase?
LPL: breaks down lipids in lipoproteins
HPL: breaks down lipids in adipocytes
Which enzyme is the rate-limiting enzyme of cholesterol synthesis?
HMG-CoA reductase
The two specialized enzymes involved in the transport of cholesterol are LCAT and CETP. What are their exact functions?
LCAT: converts cholesterol into cholesterol esters
(allows more cholesterol entry into HDL)
CETP: transfers cholesterol esters to other lipoproteins
What is the function of the enzyme HMG-CoA reductase in cholesterol synthesis?
Produces mevalonate in the SER which ultimately produces cholesterol.
