CC - LIPIDS 2 Flashcards by Sharmaine Madjid

Transport of hepatic-derived lipids

Endogenous Pathway

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IN Endogenous Pathway, ______ loses core lipids once secreted in the circulation

VLDL

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Loss of core lipids leads to conversion of VLDL to _____

remnants

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About half of the remnants are converted to ____, and half are taken in by the ____

LDL ; liver

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Mediated by HDL
Excess cholesterol from peripheral cells is transported back to the liver

Reverse Cholesterol Transport Pathway

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HDL serves to taxi cholesteryl esters to chylomicrons/VLDL remnants to liver

Reverse Cholesterol Transport Pathway

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Conversion of cholesterol into bile acids for removal

Reverse Cholesterol Transport Pathway

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Specimen Collection for Lipid Analysis

Serum
Fasting

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preferred specimen

12 hour fast preferred

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avoid _____, Presence of fat droplets suspended in a solution.

lipemia

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Lipemia affects assays by affecting absorbance due to ______ of light

refraction

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high plasma lipid concentrations can cause excessive plasma _____ and interfere with _________

turbidity ; spectrophotometric methods

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Concentration differs between men, women and children due to ________. ______ and _______

sex hormone, concentration, and age

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Higher HDL
Lower Cholesterol, triglyceride

is seen in

Women

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As aging, Men and women increase in ______, _______ and ______

total cholesterol, LDL cholesterol and triglyceride

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Colorimetric measurement procedures are less costly but are subject to ________ substances and may require _________ and ________

interfering ; extraction steps ; strong acids

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Classical method

Liebermann-Burchard

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Liebermann-Burchard is involved extraction & hydrolysis. Uses _____ & ______

sulfuric ; acetic acids

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In Liebermann-Burchard, results in formation of a ______, proportional to the __________.

green color ; cholesterol concentration

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Anything that affects HDL & LDL levels will affect cholesterol concentration-because these lipoprotein contain increased ______

cholesterol

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______ level inversely affects cholesterol level

Thyroxine

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hypothyroid associated with ________

hyper cholesterol

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hyper thyroid associated with _______

hypo cholesterol

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documented that post-menopausal women have increased LDL cholesterol

Estrogen

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altered endocrine function resulting in increased cholesterol

Pregnancy

Other factors include ______, _______, ________, and _________

hepatitis, nephrotic syndrome, emotional stress and diabetes mellitus

Dextran sulfate or phosphotungstate acid with magnesium chloride precipitates LDL and VLDL lipoproteins

Precipitation Reaction

HDL left in the supernatant is tested using cholesterol assay. The answer represents the amount of HDL in the sample

Precipitation Reaction

Elevated triglyceride levels - level exceeds 400 mg/dL

Drawbacks

Detergents or enzymes binds sites of VLDL and LDL particles. HDL is then left to react with colored products and can be measured

Homogeneous Reaction

Dsiadvantages (Homogenous Reaction)

lacks specificity for HDL

desirable range for HDL

> 60 mg/dL

gray-area for HDL

40-59 mg/dL

high risk level of HDL

< 40 mg/dL

- Enzymatic - Colorimetric - Involve the liberation of glycerol by lipase

Triglyceride Measurement Methods

recommended triglyceride range

< 150 mg/dL

triglyceride borderline high

150-199 mg/dL

very high triglyceride level

> 500 mg/dL

Friedewald estimation ( calculation ) is used for ___ measurement

LDL measurement

Total Cholesterol, Total Triglycerides and HDL with routine procedure Estimate the LDL with the following : LDL= Chol- HDL -VLDL and VLDL= Triglycerides/5

LDL Measurement

stems from the deposition of lipids in artery walls.

Arteriosclerosis

Result of malfunctions in the synthesis, transport or catabolism of lipoproteins

Hyperlipoproteinemia

Elevated lipoprotein levels

Hyperlipoproteinemia

Hyperlipoproteinemia divisions

/Hypercholesterolemia /Hypertriglyceridemia /Combined hyperlipidemia: elevation of cholesterol and triglyceride

- Linked to heart disease - Familial hypercholesterolemia (FH) - Genetic abnormality that predisposes people to high cholesterol levels, specifically LDL cholesterol. - Make cholesterol normally but lack or are deficient in active LDL receptors, so LDL builds up in the circulation . - Without the LDL receptors, LDL cannot be bound and cholesterol cannot be transferred into the cell

Hypercholesterolemia

- Imbalance between synthesis and clearance of VLDL in circulation - Deficiency of LDL or apo-C ( co-factor for LPL activity) - Chylomicrons cannot be cleared and triglycerides remain high - Normal function is for LDL to hydrolyze triglycerides carried in the chylomicrons and VLDL to give cells energy

Hypertriglyceridemia

causes of Hypertriglyceridemia

genetic abnormalities such as Familial hypertriglyceridemia

secondary causes of Hypertriglyceridemia

Hormonal abnormalities in pancreas, adrenals, pituitary and of diabetes mellitus

Hypertriglyceridemia is Influenced by many hormones such as

- Insulin, glucagon, pituitary growth hormone, adrenocorticotropic hormone (ACTH), thyrotropin, epinephrine, norepinephrine,

Hormones trigger lipase can cause _____ and _______

acute and recurrent pancreatitis

- Presence of elevated levels of serum cholesterol and triglycerides - Results from accumulation of cholesterol-rich VLDL and chylomicron remnants from defective catabolism - Risk factor for CHD - Primarily congenital

Combined Hyperlipoproteinemia

Low levels of lipoproteins

Hypolipoproteinemia

2 forms of Hypolipoproteinemia

1. Hypoalphalipoproteinemia 2. Hypobetalipoproteinemia

- Decrease in circulating HDL (< 40 mg/dL) - Lack of hypertriglyceridemia - Due to a genetic defect (Tangier Disease)

Hypoalphalipoproteinemia

Low levels of LDL cholesterol

Hypobetalipoproteinemia

Absence of lipoproteins containing Apo-b

Abetalipoproteinemia

Abetalipoproteinemia includes

LDL and VLDL

Abetalipoproteinemia results in

Difficulty in weight gain and growth Fat absorption problems RBC membrane defects Usually effects infants

activate hormone-sensitive lipase in adipose tissue, thereby increasing the supply of fatty acids for oxidation in other tissues, and inactivate acetyl-CoA carboxylase.

Glucagon and Epinephrine

regulates the levels of acetyl-CoA carboxylase and fatty acid synthase by controlling their rate of synthesis.

Insulin

complete absence of HDL with very low levels of apoAI and apoAII due to inheritance of homozygous recessive alleles.

Tangier disease

Tangier disease results to accumulation of cholesterol esters in

liver, spleen, lymph nodes, cornea, skin

(Familial chylomicronemia) – elevated chylomicron due to ineffective or insufficient LPL

Fredrickson type 1

(Primary hypercholesterolemia) - increased LDL

Fredrickson type II

(Familial dysbetalipoprotinemia) - increased IDL

Fredrickson type III

(Familial hypertriglyceridemia) - increased VLDL

Fredrickson type IV

markedly increased triglyceride

Fredrickson type V

deficiency of β –glucocerebrosidase

Gaucher’s disease

deficiency of sphingomyelinase

Niemann – Pick disease

accumulation of galactocerebroside-β – galactosidase

Krabbe’s disease

deficient α – galactosidase A

Fabry’s disease

deficiency in hexosaminidase A

Tay-Sachs disease