Lipid Profile II
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What is the primary role of Very-Low-Density Lipoproteins (VLDL) in the body?

  • Transport triglycerides from the liver to peripheral tissues. (correct)
  • Convert triglycerides into fatty acids for energy.
  • Facilitate the removal of cholesterol from the bloodstream.
  • Transport cholesterol from peripheral tissues to the liver.

    • Which apoprotein is a major structural component of Low-Density Lipoproteins (LDL)?

  • ApoC2
  • ApoA1
  • ApoE
  • ApoB100 (correct)

    • What changes occur to VLDL during its conversion to Intermediate-Density Lipoprotein (IDL)?

  • Increase in triglyceride content and particle size.
  • Gain of cholesterol and decrease in particle size. (correct)
  • Conversion of all triglycerides to phospholipids.
  • Formation of clathrin-coated vesicles.

    • How is LDL primarily removed from the bloodstream?

    <p>Through receptor-mediated endocytosis.</p> Signup and view all the answers

    What is a significant correlation between LDL levels and health?

    <p>LDL levels over 2 mmol/L are linked to fatty streak formation.</p> Signup and view all the answers

    What can mutations in the LDL receptor (LDLR) lead to?

    <p>Severe hypercholesterolaemia due to decreased LDL removal.</p> Signup and view all the answers

    Which characteristic best describes small, dense LDL particles?

    <p>They have a higher association with arterial damage risk.</p> Signup and view all the answers

    What is a primary advantage of using apoprotein measurements over cholesterol measurements?

    <p>Apoproteins reflect the functionality of lipoproteins better than static cholesterol levels.</p> Signup and view all the answers

    What is the primary characteristic of Type 4 Hyperlipidaemia?

    <p>Elevated VLDL with normal chylomicrons</p> Signup and view all the answers

    Which factor is associated with increased production of VLDL due to excessive fatty acids in the liver?

    <p>Excess Dietary Energy</p> Signup and view all the answers

    What type of lipid disorder is characterized by impaired receptor-mediated removal of chylomicrons?

    <p>Type 5: Mixed Hyperlipidaemia</p> Signup and view all the answers

    Which of the following effects is associated with chronic renal failure?

    <p>Overproduction of apoB and VLDL</p> Signup and view all the answers

    What is a notable effect of insulin resistance related to lipid metabolism?

    <p>Increased hepatic VLDL overproduction</p> Signup and view all the answers

    Which treatment is known to increase LDL levels through an unknown mechanism?

    <p>Thiazide Diuretics</p> Signup and view all the answers

    Which condition can lead to a creamy layer in plasma upon storage at 4 °C?

    <p>Type 5 Mixed Hyperlipidaemia</p> Signup and view all the answers

    Which secondary condition is associated with significantly increased VLDL formation due to retinoic acid derivatives?

    <p>Psoriasis Treatment</p> Signup and view all the answers

    What is a potential effect of oestrogen treatment on lipid profiles?

    <p>Reduces LDL and raises TAGs</p> Signup and view all the answers

    Which of the following is a common limitation of the Frederickson Classification of Dyslipidaemia?

    <p>It excludes secondary hyperlipidaemias.</p> Signup and view all the answers

    Which type of lipoprotein is primarily enhanced in uptake by scavenger receptors during atherogenesis?

    <p>Modified LDL</p> Signup and view all the answers

    What is the primary function of ApoE in relation to Intermediate-Density Lipoproteins (IDL)?

    <p>Acts as a ligand for LDL receptors</p> Signup and view all the answers

    What type of lipoproteins are more prone to modification and uptake by scavenger receptors?

    <p>Small, dense LDL particles</p> Signup and view all the answers

    Which enzyme is primarily responsible for converting free cholesterol into cholesteryl esters in HDL metabolism?

    <p>Lecithin–Cholesterol Acyltransferase (LCAT)</p> Signup and view all the answers

    What is the primary characteristic of Type 1 lipid disorder in the Frederickson Classification?

    <p>Deficiency of lipoprotein lipase or apoprotein C2</p> Signup and view all the answers

    What role does Lp(a) play in the body?

    <p>Inhibits plasminogen activity and promotes clotting</p> Signup and view all the answers

    What typically happens during the transformation of LDL particles in the blood?

    <p>They exchange cholesterol with TAGs in TRL particles</p> Signup and view all the answers

    Which characteristic is true for intermediate-density lipoproteins (IDL)?

    <p>Converted from the loss of TAGs and gain of cholesterol from VLDL</p> Signup and view all the answers

    What is a primary risk factor associated with elevated levels of Lp(a)?

    <p>Familial hypercholesterolaemia</p> Signup and view all the answers

    What aspect of small, dense LDL contributes to its pathological role in atherogenesis?

    <p>It remains in the blood longer than normal LDL</p> Signup and view all the answers

    What is the effect of apolipoprotein A1 (ApoA1) on HDL formation?

    <p>Activates lecithin cholesterol acyltransferase</p> Signup and view all the answers

    What is the primary structural component of lipoprotein (a) [Lp(a)]?

    <p>Multiple copies of kringle domains in Apo(a)</p> Signup and view all the answers

    In the context of atherogenesis, what is a key factor related to foam cell formation?

    <p>Efficient uptake of small, dense LDL by macrophages</p> Signup and view all the answers

    What defines the role of lipoprotein lipase (LPL) in lipoprotein metabolism?

    <p>Hydrolysis of TAGs in chylomicrons and VLDL</p> Signup and view all the answers

    Study Notes

    Lipid Profile II

    • Lipid Definition: Lipids are a diverse group of hydrophobic biological molecules.
    • Lipid Classification: Lipids are classified broadly, but detailed classification and nomenclature are often needed based on molecular structure.
    • Lipid Structure Examples: Various lipid structures (e.g., triglycerides, phospholipids, cholesterol) are central to understanding lipid profiles.
    • Lipid Metabolism: Metabolism encompasses the breakdown and synthesis of different lipid types.
    • Lipid Disorders: Disorders arise from imbalances in lipid metabolism, and are classified using systems like the Fredrickson classification, which details types (e.g., Type 1, 2a, 2b, 3, 4, 5). Key lipid disorders include hyperchylomicronaemia (Type 1), hypercholesterolaemia (Type 2a/2b), dysbetalipoproteinaemia (Type 3), hypertriglyceridaemia (Type 4), mixed hyperlipidaemia (Type 5).
    • Lipid Roles in Health/Disease: Lipids play crucial roles in normal bodily functions, affecting both health and disease processes. Cholesterol, in particular, is critical to many bodily functions, but abnormal amounts contribute to cholesterol-related diseases like atherosclerosis.
    • Lipid Assay Calibration: Accurate lipid assays rely on proper calibration.
    • Apoproteins vs. Cholesterol: Measuring apoproteins can provide better insight into lipid issues than cholesterol measurements alone.
    • Very-Low-Density Lipoproteins (VLDL): VLDL are assembled in the liver and transport TAGs to peripheral tissues, primarily through interactions with lipoprotein lipase in the endovascular system.
    • VLDL Metabolism: Converting VLDL to IDL involves losing TAGs and gaining cholesterol; this process leads to a decrease in particle size with a concurrent increase in density.
    • Significance of Low-Density Lipoproteins (LDL): LDL carries most cholesterol; high levels correlate with coronary heart disease risk and fatty streak formation.
    • LDL Characteristics: ApoB100 is the main apoprotein, crucial in LDL structure, synthesis and function. LDL particles are the end product of VLDL metabolism.
    • LDL Metabolism & Receptors: LDLs are removed from the blood via receptor-mediated endocytosis using LDLR (LDL receptor) binding to apoB100 (and apoE), leading to clathrin coated vesicle formation and internalization.
    • LDL Mutations: Mutations in LDLR can lead to hypercholesterolemia and reduced LDL removal.
    • Modified LDL Atherogenesis: Modified LDL (e.g. oxidized, glycated,) is taken up via scavenger receptors, a key step in atheroma formation.
    • Scavenger Receptors: Specific scavenger receptors (SRA, SRB, etc.) are involved in taking up modified LDL.
    • Small, Dense LDLs: Small, dense LDLs persist longer in the blood, more prone to modification and uptake by scavenger receptors, driving atherogenesis. They result from the exchange of lipids between LDL and other particles
    • Intermediate-Density Lipoproteins (IDL): IDL plays a critical role in lipid metabolism; ApoE is involved in targeting IDL for uptake by specific receptors. IDL is converted to LDL.
    • High-Density Lipoproteins (HDL): HDLs are formed in the liver and intestine; ApoA1 is the key structural protein. Initial HDLs are discoidal; maturation into spherical particles occurs through lipid transfer reactions and activation of LCAT, forming esterified cholesterols; additional lipid components are also added. Cholesterol transfer occurs with other lipoproteins, mainly by way of CETP and PLTP.
    • Lipoprotein (a) [Lp(a)]: Lp(a) is structurally related to LDL, composed of ApoB and Apo(a) with various isoforms. Apo(a) acts in a manner similar to plasminogen, an enzyme involved in blood clot degradation; however, Lp(a) reduces the activity of plasminogen.
    • Key Enzymes in Lipoprotein Metabolism: Lipoprotein lipase (LPL) and lecithin-cholesterol acyltransferase (LCAT) are critical for lipid transport.
    • Lp(a) and Cardiovascular Risk: Lp(a) is a significant factor in cardiovascular risk; it is not routinely assessed due to unclear risk contribution and lack of widely available treatments.
    • Fredrickson Classification: The WHO's classification system, originally based on lipoprotein patterns and now expressed as measured lipid levels; it details 5 main types (1–5).
    • Secondary Lipid Disorders: Result from diseases, treatments, or nutritional deficiencies. Underlying causes should be addressed.
    • Lifestyle Factors/Disease and Lipid Disorders: Excessive dietary energy, lipodystrophy, obesity, alcohol consumption, insulin resistance, chronic renal failure, and hypothyroidism all impact lipid metabolism.
    • Drug-Induced Lipid Disorders: Various drugs such as AIDS medications, thiazide diuretics, beta-blockers, hormonal treatments (estrogen, progestogens, androgens), and retinoic acid derivatives can alter lipid profiles.
    • Additional Secondary Causes: Cholestatic liver disease leads to Lp-X accumulation, affecting cholesterol transport, but not atherogenicity.
    • Summary: ApoB concentration differentiation assists in diagnosing hyperlipidemia.

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    Description

    Explore the intricacies of lipid profiles, including definitions, classifications, and structures of various lipids. This quiz delves into lipid metabolism and the disorders related to imbalances within lipid levels, using the Fredrickson classification system for identification. Gain insights into the critical roles of lipids in health and disease.

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