Lipids Exam 3 Flashcards
Lipids are ____ in water but ____ in organic solvents
insoluble ; soluble
Triglycerides consist of
fatty acids + glycerol
major storage form
Phospholipids consist of
glycerol backbone
2 fatty acids + phosphoric acid group
Sterol characteristics
Cholesterol most important
serves as backbone for steroids
vitamin d - 2/3 esterified form
What is a lipoprotein made up of?
Triglycerides and cholesterol (mix of apoliproteins)
What is the main role of lipoproteins?
Delivery of fuel to peripheral cells; “core” being the cargo
What is the largest and least dense of all lipoprotein particles?
Chylomicrons
Chylomicrons are produced by
Intestine and packaged with absorbed dietary lipids.
The principle role of chylomicrons is
the delivery of dietary lipids into hepatic and peripheral cells
Chylomicrons transport _____ from the _____ to the _____
Triglycerides ; intestine ; adipose cells
Apoliprotein B-48 is associated with
Chylomicrons
Very low density lipoproteins (pre beta) are made up of
mostly triglycerides
Which lipoprotein is a major carrier of endogenous triglycerides into peripheral tissue during fasting for energy and storage?
Very low density lipoproteins
APO protein B-100 associated with
Very low density lipoproteins
Low density lipoproteins
Lipoprotein A
Which lipoprotein is found in patients with type 3 hyperlipoproteinemia?
Intermediate Density Lipoproteins
Hyperlipoproteinemia puts patients at risk for
peripheral vascular disease (PVD) and Coronary Artery disease (CAD), and damages vessel wall like LDL
LDL or Beta is made up of
Cholesterol, and principally carries it.
What lipoprotein was formed as a consequence of lipolysis of VLDL?
LDL
Where is LDL readily taken up?
via LDL receptor in liver and peripheral cells
What lipoproteins are better markers for CHD risk?
the 8 LDL subclasses that are separated by ultracentrifugation or electrophoresis
Elevated levels of this lipoprotein increase risk of premature CHD and Stroke
Lipoprotein A (>30 mg/dl)
Lipoprotein A competes with _____ for binding sites on endothelium and on fibrin, which promotes clotting (stroke)
Plasminogen
Who should get their Lipoprotein A measured?
Strong family history of CHD
Developed CHD on statin therapy
Premature Aortic stenosis (high lp(a) levels)
What lipoprotein is the smallest and most dense and removes cholesterol from cells and takes it to the liver for removal?
High density Lipoproteins (reverse cholesterol transport)
High density lipoproteins are synthesized by
Liver and intestine
Which lipoprotein can exist as disk-shaped or spherical particles?
High density lipoproteins
This lipoprotein is abnormal and present in biliary cirrhosis or choleostasis
Lipoprotein X
Lipoprotein X consists of
Phospholipids and nonesterfied cholesterol
In the exogenous pathway, what enzyme converts dietary lipids into polar compounds making them amphipathic?
Lipase
Which Hydrolytic enzymes from the pancreas process lipids?
Lipase (breaks down triglycerides)
Cholesterol esterase (releases free cholesterol)
Phospholipase A (hydrolyzes phospholipids)
What is lipoprotein Lipase’s role in the exogenous pathway?
clears chylomicrons and breaks down triglycerides
Triglycerides are converted to
fatty acids by cells and ready to be used for energy
Excreted biliary cholesterol appears in
stool (fecal neutral steroids)
Triglycerides that are packaged into VLDL in the endogenous pathway are split into? by which enzyme?
They are split in IDL’s and VLDL remnants ; lipoprotein lipase
Cleaved IDL’s have two fates in the endogenous pathway:
They could either receive cholesterol esters from HDL in exchange for triglycerides, or be made into LDL in the liver by removing triglycerides
VLDL remnants have two fates in the endogenous pathway:
They could either be taken up in the liver, or be made in to LDL which delivers cholesterol to peripheral cells because of the LDL receptors.
Triglycerides inside the cell in the endogenous pathway are converted to
Free fatty acids and glycerol by the cell for energy
What enzyme transports excess cholesterol from the cell?
Lecithin cholesterol acyltransferase
What is HDL’s role in the endogenous pathway?
takes cholesterol back to the liver for disposal in bile salts
What happens if cells are full in the endogenous pathway?
LDL forms plaques
LDL receptors regulate
Cellular cholesterol biosynthesis and degradation
Hypercholesterolemia and premature atherosclerosis are abnormalities in
LDL receptor regulation
What enzyme converts cholesterol into Cholestryl ester (HDL3) in the aqueous diffusion pathway?
LCAT enzyme
HDL2 delivers cholesterol to
Liver
What is the end product of the aqueous diffusion pathway?
Cholesterol in liver directly excreted into bile or converted to bile acid.
The ABCA1 transporter is
A member or ATP binding cassette transporter family
The principle function of the ABCA1 transporter is to
enable APO A-1 from HDL to bind to cell membrane and in a detergent like mechanism, remove excess cholesterol and phospholipid from cells
HDL forms what shape to accept additional cholesterol?
discoid shape
What enzyme converts discoid shape HDL to spherical HDL?
LCAT
Cell based assay tests the
capacity of cholesterol loaded macrophages to efflux cholesterol through ABCA1 transporter
What assay provides additional knowledge of HDL function?
Cell-based assay
The cell based assay is found to be inversely corelated with
intima media thickness and with presence of CHD (disease status)
Low levels of cell based assay can be associated with
atherosclerotic cardiovascular disease
The analysis of lipids includes
total amount of all lipoproteins
What reagent is used for the colorimetric method of cholesterol and what is the name of the method?
Abell Kendall method
Liebermann buchard color reagent
Acetic acid, acetic anhydride and sulfuric acid produce green color
What is the reference method for cholesterol?
Gas chromatography mass spectrophotometry, not related sterols, cholesterol only.
What interferes with the Colorimetric- Abell Kendal method?
Hemoglobin, bilirubin, water (causes cloudiness)
What can cause increase in cholesterol values?
An increased cholesterol level can indicate an increased risk of CHD
may be caused by diabetes, estrogen, hypothyroidism
What are the pre analytical factors that influence values of cholesterol?
Stress, diurnal variation, higher in the winter
in post mortem specimens, why is blanking necessary for triglycerides?
triglycerides rapidly convert to glycerol after death
Within triglyceride methods, what is measured?
Include the hydrolysis of triglyceride to form glycerol and fatty acids; measures glycerol
In the enzymatic method for triglycerides, what two enzymes are coupled together and what do they produce?
Glycerol kinase and Glycerophosphate oxidase coupled to same peroxidase color reaction used in cholesterol
What does alkaline hydrolysis form in the colorimetric method in triglycerides?
Glycerol
What does glycerol oxidize to in the colorimetric method in triglycerides?
Formaldehyde and formic acid
What is the color development in the van handel and zilversmith reaction in triglyceride colorimetric method?
Formaldehyde and chromotropic acid will form pink color
What is the reaction in Hantzch condensation in triglyceride colorimetric method?
Formaldehyde, ammonium ion, and acetyl acetone will form diacetyl lutidine
What condition increases as HDLc decreases?
Coronary heart disease
How is HDL analyzed?
selective precipitation, divalent cations in solution of buffer, heparin, or dextran sulfate. Will precipitate VLDL and LDL leaving HDL.
What increases HDL Levels?
Weight reduction
Jogging
Estrogen
Alcohol
What could interfere with calculating LDL
presence of chylomicrons
What LDL sub particle is smaller and denser, more responsive to statin drugs and niacin, and imposes a risk of CHD?
Pattern B
What LDL sub particle is larger and less dense, and is more responsive to fibrates or niacin. And lowers triglyceride, but has side effects of flushing?
Pattern A
What drugs can be used to manage lipid levels?
Statins and Repatha
What is the primary prevention for those at risk of CVD?
Statins, Atorvastin, Fluvrastatin.
Statins are
HMG- COA reductase inhibitors, they are lipid lowering medication by decreasing LDLc.
What are the side effects of statins?
Myalgia, rhabdomyolysis, liver damage
Repatha can be defined as
monthly injections to decrease LDLc, it is beneficial for those with myalgia from statins.
