Lipid transport simple Flashcards
outline chylomicron transport
- Lipids are loaded into chylomicrons in the small intestine and move to the lymph via lacteal in the villi and then are emptied into the blood via the thoracic duct into the left subclavian
- At the walls of capillaries, chylomicrons are partially metabolised by lipoprotein lipase (LPL) supplying the cells with the lipids they need
- Once the lipid content of the chylomicrons falls below 20% it becomes a chylomicron remnant and travels to the liver to finish being broken down
why is LDL known as bad cholesterol
has a longer half life meaning it is more likely to be oxidised
outline oxidation of an LDL
LDL is phagocytksed by macrophages and become foam cells –> contribute to atherosclerosis
having low LDL
reduces the risk of foam cell formation and therefore atherosclerosis risk reduced
VLDL
very low density lipoprotein
IDL
intermediate density lipoprotein
LDL
low density lipoprotein
HDL
high density lipoprotein
outline VLDL, IDL and LDL metabolism
- TAG produced/ stored in the liver is released within VLDL (containing mostly lipids and some cholesterol esters)
- VLDL binds to lipoprotein lipase on the outside of cells seeing lipids and depletes its TAG content –> becoming IDL
- IDL binds to more LPL and depletes its TAG store until it is nearly completely gone –> become LDL
- LDL enters hepatocytes or cells that need cholesterol
- LDL gets endocytose and digested by lysosomes
how does the LDL know which hepatocyte to enter
hepatocytes and cells expressing receptors for the ApoB-100 ligand found on the LDL
HDL is known as
good cholesterol
why is HDL good cholesterol
removes excess cholesterol from peripheral tissue therefore decreasing chance of atherosclerosis
HDL metabolism
- Empty HDL particle is released from the liver and receives excess cholesterol from body cells and Ldl
- It then transports this to the liver or stereogenic cells
stereogenic cells
can be used to produce steroid hormones and bile salt
