Lipids! Flashcards
what is the difference between saturated and unsaturated fatty acids? What are linoleic and linolenic acids? What are the polyunsaturated fatty acids?
saturated: no C=C bonds
- usually solids at room temp
unsaturated: one C=C bond (polyunsaturated = more than one C=C bonds; omega fatty acids)
- liquids at RT
linoleic and linolenic acids are fatty acids in plants and must be ingested via diet
triglycerides from plants are what form at room temperature? what about the ones from animal fat?
plant = polyunsaturated = oils at RT
animal sources = saturated fatty acids = solids at room temperature
what is the structure of lipoproteins, and how does their size relate to what kind of lipoprotein they are?
surface: phospholipids, free cholesterol, and apolipoproteins (proteins)
- amphiphatic
core: hydrophobic cholesterol esters and triglycerides
the bigger the lipoprotein, the more core lipids it is carrying
- eg VLDL and chylomicrons, and even LDL
what kind of apolipoproteins are involved in the different kinds of lipoproteins?
APO A I and II: HDL
APO B48: chylomicrons only
APO B100: LDL and VLDL
APO C I - III and APO E: VLDL
where are chylomicrons made, what do they do to plasma, and what is their function?
made in intestines
large size scatters light = plasma turbidity and also creamy top layer on plasma
transport dietary lipids (exogenous triglycerides) to both the liver and peripheral cells
where are VLDL molecules made, what is their function, and what can increase their production?
made in the liver
transport endogenous (hepatic derived) lipids FROM the liver TO the peripheral cells
excess dietary intake of carbs, saturated fatty acids, and trans fatty acids enhanced the liver to make triglycerides
what are IDLs and what can they cause in excess and why?
they’re VLDL remnants, as VLDLs turn into LDLs.
can cause PVD and CAD because these particles are damaging to blood vessels
(also seen in high amounts with people with hyperlipoproteinemia due to abnormal form on APO E)
what causes foam cells?
macrophages that have taken up too much LDL (since LDL can filtrate into the extracellular space of the vessel walls)
early precursor to atherosclerotic plaque
what is the function of LDL?
takes endogenous cholesterol to the arteries as plaque from the liver
what is the function of HDL? Where is it made?
transport cholesterol from the arteries back to the liver via the reverse cholesterol transport pathway
made in both the liver and intestine
during the process of digestion, ________ ______ first turns ________ lipids into more _____ compounds with amphipathic properties by cleaving off ______ _____.
pancreatic lipase turns dietary lipids into more polar compounds with properties by cleaving off fatty acids
- triglycerides to mono/di-glycerides
- cholesterol esters to free cholesterol
- phospholipids to lysophospholipids
what happens when the newly formed amphipathic lipids in the intestinal lumen aggregate with bile salts?
they turn into micelles, and then lipid absorption occurs when the micelles come into contact with the micro villus membranes of the intestinal mucosal cells
- cholesterol less good than triglycerides at being absorbed
chylomicrons are first secreted into ______ ______ and the enter circulation via the _____ duct. What do they then interact with on various tissues? What do they become when they are transported back to the liver?
first secreted into lymphatic vessels and enter circulation via the thoracic duct
interact with proteoglycans on various tissues
broken down into VLDLs in the liver (which then go to the peripheral cells)
what happens to turn VLDL into LDL?
VLDL loses core lipids that will turn it into LDL
what happens when proteoglycans interact with chylomicrons?
promotion binding of LPL which hydrolyzes triglycerides on chylomicrons
- free fatty acids used by cells for energy
- excess fatty acids re-esterized for long-term energy storage
HDL can also transfer _________ ______ to chylomicrons and _____ to the liver. The cholesterol on HDL is transferred to ____ and then is excreted into ____
can also transfer cholesteryl esterase to chylomicrons and VLDL to the liver.
cholesterol on HDL transferred to LDL and excreted into bile
the relationship between heart disease and dyslipidemias is what?
stems from deposition of lipids mainly in the form of esterified cholesterol in artery walls. This deposition results in fatty streaks (excess fat in macrophages in the sub endothelial cells) that can turn into plaques later in life
- plaques in legs/arms = peripheral vascular disease
lipid deposits in the skin form nodules called _________?
xanthomas (usually due to a genetic abnormality)
there is a strong correlation between hypercholesterolemia and ____ ____? what is a genetic abnormality that predispose people to have high cholesterol
CAD mortality
familial hypercholesterolemia
- heterozygotes more common to see than homozygotes
- can see xanthomas (cholesterol deposits) under tendons or the cornea
how do you treat hypercholesterolemia?
statin: a HMG-CoA reductase inhibitor, and this adds LDL receptors to liver for removal of LDL from circulation
increased cholesterol levels are associated with what four things? what about decreased cholesterol levels?
increased: hypothyroidism, liver disease, renal disease, and diabetes
decreased: hyperthyroidism, inherited defects, malabsorption, and impaired liver function
what things are associated with increased and decreased HDL?
increased: progesterone levels, exercise, and blood pressure medications
decreased: progesterone levels, obesity, smoking, triglyceride increase, and diabetes
increased triglycerides is increased in secondary disorders such as?
hormonal abnormalities with the pancreas (insulin/glucagon), adrenal glands (ACTH), pituitary (GH), or diabetes mellitus (shunting of glucose into the pentose pathway that increase fatty acid synthesis), or alcohol consumption
can accelerate atherosclerosis process
severe hypertryglyceridemia can cause acute and recurrent _________. Usually due to a deficiency of what two things?
pancreatitis
due to APO C2 or LPL that will hydrolyze triglycerides for cells for energy
what are causes for increase glycerol levels (increased triglycerides)?
mannitol infusion, nitroglycerine use, hemodialysis
familial combined hyperlipidemia is caused by an increase in what two things? what are these elevations due to?
increase in elevated cholesterol, triglycerides, or both. Due in part to excessive hepatic synthesis of apoprotein B (leads to increased VLDL secretion and increased production of LDL from VLDL)
familial dysbetalipoproteinemia (hyperlipidemia type III) is due to what?
accumulation of cholesterol-rich VLDL and chylomicron remnants (eg IDL) due to defective catabolism of these particles
- increased total cholesterol (200 - 300 mg/dL) and increased triglycerides (300 - 600 mg/dL)
- increased PVD and CAD risk
mixed hypertriglyceremia/hypercholesterolemia can be due to what three things?
diabetes mellitus, nephrotic syndrome, or familial
decreased HDL is assisted with what disease?
Tangier’s disease (hypoalphaproteinemia)
cholesterol measurement is dependent on ________ for ___ hours
fasting for 12 hours
what is the most common enzymatic sequence for measuring cholesterol? What things should be avoided during cholesterol analysis?
cholesteryl ester hydrolase: cleaves fatty acid residues from cholesteryl esters to make free cholesterol that gets reduced by cholesterol oxidase to make H2O2 to make a color reaction
avoid reducing agents: Vit C and bilirubin
also avoid turbidity
HDL analysis uses:
ultra centrifugation or selective precipitation
what is the friedewald calculation for LDL-C?
total cholesterol - HDL - trig/5
where VLDL is trig/5 as long as trig doesn’t exceed 400 mg/dL)
how long do you need to fast for triglyceride analysis?
12 - 16 hrs
what is the reference range for
- total cholesterol
- HDL-C
- LDL-C
- triglycerides
- glucose
(all in mg/dL)
total cholesterol: 140 - 200
HDL: 40 - 75
LDL: 50 -130
triglycerides: 60 - 150
glucose: 75 - 100
cholesterol can be falsely ______ due to _____ when patient is laying down
falsely decreased due to hemodilution (diluted blood)
