Exam 3 – Dr. Sullivant Lipid Metabolism Flashcards
What are the types of lipids?
Triglycerides
Phospholipids
Cholesterol
What are fatty acids?
The basic moiety of all lipids
They are long chain hydrocarbon organic acids
What are triglycerides used for?
Primarily energy production
What is the composition of triglycerides?
3 fatty acids and 1 glycerol
What are cholesterol and phospholipids used to do?
Make cell membranes
What are lipoproteins?
A carrier service for lipids in the plasma
What do lipoproteins do?
Transport lipids to and from liver
Transport lipids to other tissue for use/storage
What are lipoproteins made of?
Cholesterol
Triglycerides
Phospholipids
Protein
What are the types of lipoproteins?
Chylomicrons
Low density lipoproteins (LDL)
Very low density lipoproteins (VLDL)
High density lipoproteins (HDL)
What do chylomicrons do?
Carry digested fat from intestines to lymphatics
What do LDLs contain?
Higher cholesterol
What do VLDLs contain?
High triglycerides
Moderate cholesterol
What do HDLs contain?
Lower cholesterol
What is bile made by?
Hepatocytes at a rate of 1/2 to 1 liter/day
Where is bile stored?
Gall bladder
What are the 2 major functions of bile?
Fat digestion
Excretion of wastes, including cholesterol and bilirubin
What is the composition of bile?
Bile salts make up 50% of composition
What are bile salts made from?
Cholesterol
When is bile released from the gall bladder?
When fat reaches the duodenum
What is the contraction that releases bile stimulated by?
Cholecystokinin
What do bile salts do?
Emulsify fat globules and then form micelles that allow further digestion/absorption of fats
What happens to bile salts once the emulsify fat globules?
They are left behind in the GI tract lumen and recycled back to the liver for repeat use
What does an increase in chylomicron in the serum after a meal do?
Causes turbidity or whitish color
How long does it take for chylomicrons to be cleared in normal animals?
Within 30 minutes
Describe micelles
Have water soluble and fat soluble portions that surround the fat
Allow water soluble enzymes to act further on fat for digestion Shuttle broken down fats to the intestinal brush border and release them into the intestinal cells
What does lipoprotein lipase do?
Break down chylomicron to release triglycerides and free fatty acids immediately
What are the steps of lipid metabolism?
Lipolysis
β-oxidation
TCA cycle
Oxidative phosphorylation
What happens in lipolysis?
Triglycerides hydrolyzed to FA and glycerol
What does hormone sensitive lipase do?
Signals the release of stored fat from adipose when cells need energy
Turns stored fat into free FA in the bloodstream
What are the ketones?
Acetoacetic acid
β hydroxybutyric acid
Acetone
What does the liver do if lipid concentrations are too elevated?
It degrades the excess fatty acids into kets-acids (ketones)
What does insulin do?
Increases CHO utilization and fat storage
Increased fat mobilization for energy
What activates hormone sensitive lipase?
Epinephrine
Glucocorticoids
Growth hormone
What does leptin do?
Signal satiety to hypothalamus
Decreases fat storage
Decreases appetite
What is leptin produced by?
Full adipocytes
