Lipids Skildum Flashcards
Most calorically dense food?
Fat
What particle functions to promote cholesterol homeostasis?
HDL
They take excess cholesterol from the tissues back to the liver where it can be converted into bile salts etc.
Which lipoprotein activates an extracellular lipase in capillary beds?
ApoCII
*Activates lipoprotein lipase
What can we do with excess de novo glucose in our bodies?
Make Fatty acids!
Main storage form of energy in our body?
Triacylglycerol
Key intermediate between fatty acids and prostaglandins & leukotrienes and thromboxanes?
Arachidonic acid!
How do prostaglandins and thromboxanes play into achalasia?
They can chemically signal a tonically contracted LES
What acts to break up fat down into a lot of little tiny globs of fat?
Bile acid salts
Where are lipases secreted from?
pancreas
At what point does fat composition change after swallowing?
In the small intestine
What hormones promote secretion of bile and lipases into the lumen of the gut?
*Cause contraction
Secretin & Cholecystokinin (CCK)
Why do people with CF often have malabsorption of lipids?
Secretion of lipases is deficient because of pancreatic duct blockage
Where does pancreatic lipase cut on triacylglycerol?
1 and 3 positions
What is the end product of pancreatic lipases function?
2 fatty acids + 2-monoacylglycerol
What do the products of pancreatic lipase combine with once taken up by gut epithelial cells before they become chylomicrons that enter the lymph system and then the blood?
ApoB48
What are the products of cholesterol esterase?
Cholesterol and a free fatty acid
Positions of fatty acids on phospholipids?
1 and 2 positions
What is fat consumed as phospholipids broken down by?
PLA2
Major apoprotein produces by gut epithelial cells?
ApoB48
So what things go from the lumen to the blood and what goes from the lumen to the lymph?
Amino acids and glucose go into the blood
Chylomicrons go into the lymph (they bypass portal blood that goes directly into the liver)
Main difference between chylomicrons and VLDL?
Apoprotein composition: chylomicrons ApoB48, VLDL has ApoB100
What produces ApoB48 in intestinal epithelial cells?
RNA Editing…The full length unedited transcript of the B-apoprotein gene produces ApoB-100
Structure of chylomicron?
Phospholipid outside
TAG on inside
ApoB48 acts as a nucleus that these things coalesce around
Nascent chylomicron?
ApoB-48 only
No metabolic fate
How are nascent chylomicrons matured?
Addition of other apoproteins that are donated by HDL…HDL gives then ApoCII and ApoE
Role of ApoCII?
allow chylomicron to deliver fatty acids to different tissues…LipoProteinLipase on extracellular side of capillary bed contacts ApoCII and fatty acids are taken up by tissue!
Where is LPL located?
Capillary beds of muscle and adipose tissue
When chylomicrons lose most of their fatty acids what happens?
Become chylomicron remnants and are reuptaken by the liver! Recycled
Role of VLDL?
Release fat that is produced by dietary carbohydrate
How does VLDL go from nacent to competent?
It has to pick up peripheral lipoproteins like ApoCII and ApoE from HDL
What happens when VLDL is floating in the blood?
ApoCII interacts with LPL (just like a chylomicron) and you get FA cleavage…FA enter cell. If it is an adipose cell, it is being repackaged as TAG but if it is a muscle cell it will be oxidized for fuel
Order of LDLs in terms of fat content
VLDL >IDL >LDL >HDL
*HDL has much more protein and less fat
What particle functions to distribute dietary fat to tissues?
Chylomicron
Which particle functions to distribute fat synthesized from carbs to tissues?
VLDL
