Lipids and Lipoproteins Flashcards
what are the 3 major sources of triacyglycerol?
dietary = processed in intestinal cells
de novo TAG in hepatocytes and adipocytes
What does HDL give to VLDL, IDL, and LDL?
cholesterol esters
What is the composition of chylomicrons like relative to HDL?
chylomicrons = mostly TAGs, least protein HDL = least TAGs, most protein
What is the function of lipoproteins?
serve as vehicles for transport of cholesterol, cholesterol esters, TAGs, and fat soluble vitamins
What is a xanthoma?
irregular yellow patch or nodule on skin caused by deposition of lipids
seen in type I and II hyperlipoproteinemia
What are the 5 different types of lipoproteins?
chylomicrons VLDL IDL LDL HDL
What does HDL exchange with chylomicron?
ApoC-II and ApoE
How is the uptake of LDL accomplished?
receptor-mediated endocytosis –> clathrin coated pit –> vesicle –> endosome –> lysosome –> cholesterol and amino acids used
*LDL receptor gets recycled and put back on the cell surface
What apolipoproteins are on HDL?
ApoA-I
ApoC-II
ApoE
What apolipoprotein is on LDL?
ApoB-100
What is the function of ApoB-100?
facilitates transport of everything VLDL, IDL, and LDL; made in the liver
What is the function of ApoB-48?
facilitates transport
What apoliproteins are on VLDL?
apoB-100
apoC-II
ApoE
How many calories are stored in the body in protein?
24000 = muscle
What is the function of ApoC-II?
activates lipoprotein lipase
Rank the 5 types of lipoproteins by size, largest to smallest.
chylomicrons VLDL IDL LDL HDL
How many calories are stored in the body in TAGs?
100,000 = fat and muscle
What is the function of ApoE?
facilitates uptake into liver
What is is type II hyperlipoproteinemia?
aka familial hypercholesterolemia
defect in LDL receptor that recognizes ApoB100 –> can’t uptake into cells
heterozygous = cholesterol 300-500
homozygous = >800
What are the main beneficial roles of HDL?
scavenges and removes LDL from periphery and takes it to the liver to be recycled and processed
antioxidant and anti-inflammatory properties
keeps endothelium of vessels healthy
What do VLDL, IDL, and LDL all give to HDL?
CETP = cholesterol ester transfer protein Triacylglycerols = TG Phospholipids = PL
What does HDL exchange both ways w/ VLDL?
Apo C-II, ApoE
What is type I hyperlipoproteinemia?
inability to hydrolyze TAGs in chylomicrons and VLDLS
either deficiency in LPL or apoC-II
LPL deficiency is worse - see in infancy
Plasma TAG levels >1000
What apolipoproteins are on IDL?
ApoB-100
ApoE
How many calories are stored in the body in glycogen?
600 kCal = liver and muscle
What is the structure of lipoproteins?
outer shell = monolayer of phospholipids, cholesterol, and apolipoproteins
inner core: hydrophobic TAGs, cholesterol esters
How many calories are stored in the body in glucuse?
40 kCal = blood
What apolipoproteins are on chylomicrons?
ApoB-48
ApoC-II
ApoE
How do you treat type II hyperlipoproteinemia?
heterozygous ppl respond to diet, statins and bile acid binding resins
homozygous need LDL apheresis and liver transplantation
