15. Lipid Metabolism, Pathophysiology and Lab Tests Flashcards
3 components of a chylomicron
- Cholesterol
- Phospholipids
- Protein (coat)
Effect of insulin on lipolysis?
Deceases lipolysis by reducing conversion of fat cell lipid stores into blood fatty acids
What is linolenic acid an example of?
Polyunsaturated FA
What is analyzed in the precipitation separation method for HDL measurement?
The SUPERNATANT is analyzed for HDL
More common method of HDL measurement?
Homogenous enzymatic colorimetric mehod
Effect of insulin on lipid synthesis?
Increases lipid synthesis (forces fat cells to take in blood lipid => converted to trigs)
Cause of turbid bottom layer
VLDL
Which apolipoprotein to test in the lab for HDL?
A1
When chyme enters duodenum, it triggers a hormonal signal called _________
Cholecystokinin
Causes a cream layer on top of plasma after overnight refrigeration
Chylomicrons (lowest density)
Main function of apolipoproteins?
Direct lipids to correct target
What does a turbid sample indicate?
Trig levels > 4 mmol/L
Liver synthesis of trigs - 2 sources?
- FAs in adipose tissue
- Carbs from diet
Triglycerides RI
< 1.70 mmol/L
Hormone sensitive lipase activity is promoted by ________ and inhibited by _________
Promote - growth hormone
Inhibit - insulin
What is familial hypecholesterolemia? Consequences?
Defective LDL receptor = no LDL internalization
Leads to atherosclerotic plaque formation
4 functions of cholesterol
- Cell membranes
- Precursor of bile acids
- Precursor for all steroid hormones
- Vitamin D
____________ cannot be synthesized in the human body
Essential fatty acids
Main function of trigs?
Provide energy for cells and component of cell membranes
4 forms FAs can exist as
- Free fatty acids
- Triglycerides
- Phospholipids
- Cholesterol esters
What do patients w/ primary hyperlipidemia develop
Xanthomas
Function of cholecystokinin
Triggers gall bladder release of bile into duodenum
Which apolipoprotein to test in the lab for LDL?
B100
Difference between abetalipoproteinemia and dysbetalipoproteinemia
Abeta- = Defective apoprotein B synthesis
Dysbea- = defect in Apo-E synthesis
4 major lipids present in plasma
- Fatty acids
- Triglycerides
- Phospholipids
- Cholesterol
6 functions of lipids
- Storage/source of energy
- Cell membrane structure
- Chemical messengers
- Vitamins
- Shock absorber
- Insulation
What does a decrease of Apo C2 lead to?
Increased CMs and trigs
Reason for lipid profile with elevated trigs but normal total chol?
Patient didn’t fast = need recollection
Molecule that determines how trigs are used
Lipoprotein lipase
What makes lipids soluble in blood?
Lipids are combined with protein (lipoprotein)
2 interfering agents w/ cholesterol measurement?
Reducing agents (vitamin C, bilirubin)
3 conditions where fecal fat is elevated
- Chronic pancreatitis
- Celiac disease
- Short bowel syndrome
5 drugs used to manage lipid disorders
- statins
- fibrate
- bile acid binding resins
- ezetimibe
- nicotinic acid
When is it not possible to use the LDL formula
When trigs > 4.5 mmol/L
2 functions of phospholipids
- Cell membrane
- Lipoprotein outer shell
Cause of primary hyperlipidemia?
Absent/defective LPL, LDL receptors or apolipoproteins
Function of Apo C2
- Activates lipoprotein lipase (LPL)
- Stored on HDL for transfer to chylomicrons and VLDL
