Lipids Flashcards
Chylomicrons
Transport exogenous lipids from intestines to tissues.
VLDL/IDL/LDL
Transport endogenous lipids from liver to tissues.
HDL
Transports excess lipids from tissues back to liver.
ApoB100
Helps with endocytosis of LDL
ApoCII
Activates LPL to free fatty acids from the triglycerides
ApoE
Helps the lipoprotein bind to the cell.
Pathway of chylomicrons
Intestines –> Lymph –> Blood –> ApoCII frees fatty acids –> Back to liver for disassembly
What tissues have the greatest need for fatty acids?
Adipose tissue, muscle tissue, adrenal glands, gonads, lactating mammary glands
Pathway of Lipoproteins
VLDL + ApoB100 leave liver –> blood –> ApoCII and ApoE picked up from HDL –> ApoCII activates LPL, FFAS freed –> IDL –> Returns ApoCII and ApoE –> LDL Gives up cholesterol
What happens to LDL particles?
They are returned to the liver or scavenged by macrophages
What apolipoprotein is associated with foam cells?
LDL (foam cells formed when macrophages take up LDL)
Pathway of HDL
HDL + ApoE + ApoCII leave liver –> Gives ApoE and ApoCII to VLDL –> Takes them back from IDL –> Picks up excess cholesterol for delivery to the liver
Where does ketogenesis occur?
Liver - mitochondria
Where does cholesterol synthesis occur?
Liver - cytosol
What tissues synthesize cholesterol?
Brain, ovaries, testes, intestines, liver (BOTIL)
What process is mevalonate associated with?
Cholesterol synthesis
How do statins work?
They compete with HMG CoA for access to HMG-CoA reductase (short half-life)
What regulates cholesterol synthesis? Where is it located?
SREBP in ER
What phenotypes does SREBP impact?
HMG-CoA reductase, LDL receptor expression
What hormones can be made from cholesterol?
Progesterone, aldosterone, cortisol, estradiol, testosterone (PACET)
In what process does succinyl CoA serve as a source of CoA?
Oxidation of ketone bodies
Where do animals get fatty acids from?
- Diet
- Storage (adipocytes)
- Converting carbohydrates to fats
- Autophagy
Where are triglycerides stored?
-Adipose tissue
- Between muscle fibers and within muscle cells
What tissues respond to signals from glucagon?
Liver & skeletal muscle