Lipid transport Flashcards
What are the classes of lipids?
Triacyl glycerol Fatty acids Cholesterol Cholesterol esters Phospholipids
How are lipids transported in the blood?
Bound to Albumin because they are not soluble
What are lipoprotein particles?
Small assemblies of lipid molecules surrounded by polar molecules constructed in the liver.
What are the classes of lipoprotein particles?
Chylomicrons
VLDL
LDL
HDL
What do Chylomicrons do?
Carry lipids (triacylgylcerols) from food in the intestine to the tissues.
When are Chylomicrons present in the blood?
4-6 hours after a meal
What are VLDLs?
Formed in the liver for storage of energy. They’re rich in triacylglycerols and carry lipids from the liver to tissues
What are LDLs?
Formed in liver and contain lots of cholesterol. Carry cholesterol from the liver to tissues
What is a high level of LDLs associated with?
A higher risk of atherosclerosis
What are HDLs?
Formed in the tissues and carry cholesterol from tissues to liver
How are triacylglycerols transferred from chylomicrons and VLDLs?
Endothelial cells of capillaries have lipase which binds the chylomicrons and VLDL. Triacylglycerols and cleaved into Glycerol and fatty acids. Fatty acids enter the cell.
How is cholesterol transferred from LDLs?
LDL receptors bind to LDL, endocytose cell and cholesterol ester released then cleaved into cholesterol and fatty acid.
How does HDL transport cholesterol back to the liver?
HDL synthesised as shells in the liver. Sequesters cholesterol from the capillaries then carries it back to the liver.
What are Hyperlipoproteinaemias?
Raised levels of one or more lipoprotein classes.
What can cause Hyperlipoproteinaemia?
Over production or Under removal due to defective enzyme, receptors or apoproteins
