Understanding Blood Lipids Lecture
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Questions and Answers

What is the primary role of LDL in the body?

  • Reverse transport of cholesterol
  • Main carrier of cholesterol (correct)
  • Main carrier of triglycerides
  • Free cholesterol regulation

    • HDL is considered protective against cardiovascular disease.

    True

    What is the consequence of mutations in the LDL receptor?

    Severe inherited forms of hypercholesterolemia

    Familial Hypercholesterolaemia follows an ________ dominant inheritance pattern.

    <p>autosomal</p> Signup and view all the answers

    Match the following types of hyperlipidaemia with their characteristics:

    <p>Type 1 = Chylomicrons, Triglycerides, Rare Type 2a = LDL, Total Cholesterol, Common Type 4 = VLDL, Triglycerides, Common Type 5 = Chylomicrons &amp; VLDL, Triglycerides, Rare</p> Signup and view all the answers

    What is the primary function of triglycerides in the body?

    <p>Energy storage</p> Signup and view all the answers

    Cholesterol is solely derived from dietary sources.

    <p>False</p> Signup and view all the answers

    What component helps to transport insoluble lipids in blood?

    <p>Apoproteins</p> Signup and view all the answers

    The backbone of triglycerides consists of ______ and three fatty acid residues.

    <p>glycerol</p> Signup and view all the answers

    Match the following lipid types with their functions:

    <p>Fatty Acids = Metabolic fuels Cholesterol = Essential component of cell membranes Triglycerides = Energy source Lipoproteins = Transport of lipids in the blood</p> Signup and view all the answers

    Which of the following statements is true regarding lipids?

    <p>Lipids can serve as metabolic fuels.</p> Signup and view all the answers

    Dyslipidaemia refers to a disorder of lipid metabolism.

    <p>True</p> Signup and view all the answers

    Name one role of Clinical Biochemistry laboratories in relation to blood lipids.

    <p>Analyzing blood lipids</p> Signup and view all the answers

    Which apoproteins are associated with chylomicrons?

    <p>A1, B48, C2 and E</p> Signup and view all the answers

    HDL is the main carrier of dietary triglycerides.

    <p>False</p> Signup and view all the answers

    What is the primary function of VLDL?

    <p>Main carrier of endogenously produced triglycerides</p> Signup and view all the answers

    The major apolipoproteins present in LDL are ___ and ___

    <p>B100</p> Signup and view all the answers

    Match the following lipoproteins with their main characteristics:

    <p>Chylomicrons = Main carrier of dietary triglycerides VLDL = Main carrier of endogenously produced triglycerides LDL = Main carrier of cholesterol HDL = Protective function</p> Signup and view all the answers

    Which lipoprotein has the highest percentage of protein?

    <p>HDL</p> Signup and view all the answers

    Dyslipidaemia can be caused by defects in apoproteins.

    <p>True</p> Signup and view all the answers

    What is the main role of lipoproteins?

    <p>Interorgan fuel, distribution, maintain cholesterol pool</p> Signup and view all the answers

    The density of HDL is between ___ and ___ g/mL.

    <p>1.063, 1.210</p> Signup and view all the answers

    What is the mean diameter of VLDL?

    <p>43 nm</p> Signup and view all the answers

    What is the major component of chylomicrons?

    <p>Triglyceride</p> Signup and view all the answers

    Chylomicrons contain ApoB-48 as their only apolipoprotein.

    <p>False</p> Signup and view all the answers

    What is the mean diameter of chylomicrons?

    <p>500 nm</p> Signup and view all the answers

    Chylomicrons primarily carry dietary __________.

    <p>triglycerides</p> Signup and view all the answers

    Match the following apolipoproteins with their functions:

    <p>ApoB-48 = Major apolipoprotein of chylomicrons ApoC2 = Activates lipoprotein lipase ApoE = Facilitates endocytosis of chylomicron remnants ApoC3 = Regulates lipid metabolism and inhibits lipoprotein lipase</p> Signup and view all the answers

    Which apolipoprotein is NOT part of chylomicrons?

    <p>ApoA1</p> Signup and view all the answers

    Chylomicrons are transported directly into the blood circulation.

    <p>False</p> Signup and view all the answers

    What process allows chylomicron remnants to enter cells/tissues?

    <p>Endocytosis</p> Signup and view all the answers

    The density of chylomicrons is approximately __________ g/mL.

    <p>0.93</p> Signup and view all the answers

    Which of the following lipoproteins is primarily involved in the endogenous pathway?

    <p>VLDL</p> Signup and view all the answers

    What is the major component of VLDL?

    <p>Triglyceride</p> Signup and view all the answers

    VLDL is synthesized exclusively in the intestines.

    <p>False</p> Signup and view all the answers

    What role does ApoC2 play in the metabolism of VLDL?

    <p>Activates lipoprotein lipase</p> Signup and view all the answers

    VLDL is secreted into the circulation from the ___.

    <p>liver</p> Signup and view all the answers

    Which of the following is a characteristic of LDL?

    <p>Can penetrate vascular endothelium</p> Signup and view all the answers

    VLDL contains more cholesterol than triglycerides.

    <p>False</p> Signup and view all the answers

    What happens to VLDL after it reaches peripheral tissues?

    <p>It is endocytosed via ApoE.</p> Signup and view all the answers

    The typical density range of VLDL is between ___ and 1.006.

    <p>0.95</p> Signup and view all the answers

    Which apoprotein is most associated with VLDL?

    <p>ApoB-100</p> Signup and view all the answers

    Study Notes

    Blood Lipids Lecture Notes

    • Blood lipids are essential for cellular structure and metabolic pathways, providing energy storage as well as structural components of cells.
    • Lecture aims include understanding lipid biochemistry and metabolism, describing lipid disorders, outlining the role of clinical biochemistry labs in analyzing blood lipids, and explaining dyslipidaemia treatment.

    Preparation

    • Slides contain chemical structures of cholesterol, a free fatty acid, a triglyceride, and a phospholipid.
    • Active revision is recommended involving eating pizza after the lecture.

    Aim and Objectives

    • The lecture's aim is to introduce blood lipids.
    • Students will be able to understand lipid biochemistry and metabolism.
    • Lipid disorders and clinical diseases will be described.
    • The role of clinical biochemistry labs in blood lipid analysis will be examined.
    • Treatment options for dyslipidaemia will be explained.

    Essential to Life!

    • Lipids have diverse roles in bodily functions, including cell structure maintenance and energy storage.

    Major Groups of Lipids

    • Fatty acids are metabolic fuels, stored as triglycerides, and have long carbon chains with a carboxyl group.
    • Triglycerides are energy sources with glycerol backbones and three fatty acid residues.
    • Cholesterol is essential for cell membrane components, prevalent in diet and liver.
    • Lipoproteins combine lipids with apoproteins for solubility and transport.

    Apoproteins

    • Apoproteins are multifunctional proteins that transport insoluble lipids into the blood's hydrophilic environment.
    • Apoproteins maintain lipoprotein structure, regulate enzymes acting on lipoproteins, and facilitate receptor recognition.
    • Defects in apoproteins can cause dyslipidemias.
    • Specific apoproteins are associated with different parts of the body (e.g., intestines, liver, macrophages).

    Lipoproteins

    • Lipoproteins are complexes of lipids and apoproteins crucial for lipid transport within the body.
    • Lipoproteins are responsible for interorgan fuel, distribution, and cholesterol pool maintenance.

    Key Lipoprotein Classes

    • Chylomicrons transport dietary triglycerides.
    • VLDL transports endogenously produced triglycerides.
    • LDL transports cholesterol.
    • HDL is involved in cholesterol reverse transport.

    Exogenous Pathway - Chylomicrons

    • Chylomicrons originate in the intestines and carry dietary triglycerides through the lymphatic system.
    • Lipoprotein lipase (LPL) breaks down triglycerides into fatty acids for cellular use.
    • Chylomicron remnants are cleared by the liver.

    Endogenous Pathway - VLDL

    • VLDL originates in the liver and carries endogenously produced triglycerides.
    • LPL breaks down VLDL triglycerides into fatty acids.

    Endogenous Pathway - LDL

    • LDL delivers cholesterol to peripheral tissues.
    • LDL receptors on cells remove LDL cholesterol for cellular use.

    Endogenous Pathway - HDL

    • HDL is involved in reverse cholesterol transport, removing excess cholesterol from peripheral tissues.
    • HDL delivers cholesterol to the liver for excretion.

    Key Lipoprotein Classes (Table Summary)

    Chylomicrons: Triglyceride rich; large; low density; carry dietary triglycerides.
    VLDL: Triglyceride rich; medium size; low density; carry endogenous triglycerides LDL: Cholesterol rich; medium size; low density; deliver cholesterol to cells HDL: Protein rich; small; high density; remove cholesterol from cells

    Dyslipidaemia

    • Elevated lipid levels; clinical manifestations often involve elevated LDL and triglycerides.
    • WHO/Fredrickson classification details types of hyperlipidaemias, including phenotype, lipoprotein, elevated levels, increased lipid fraction, and plasma appearance.

    Classification - Hypercholesterolaemia

    • Primary and secondary hypercholesterolaemia are categorized.
    • Causes of primary hypercholesterolaemia include familial hypercholesterolaemia and autosomal recessive hypercholesterolaemia.
    • Secondary hypercholesterolaemia can be linked to diabetes, renal diseases, anorexia, and liver disease.

    Classification - Hypertriglyceridaemia

    • Primary and secondary hypertriglyceridaemia subtypes are categorized.
    • Primary causes include familial combined hyperlipidemia, lipoprotein lipase deficiency, and familial endogenous hypertriglyceridemia.
    • Secondary causes involve pancreatitis, systemic lupus erythematosus (SLE), alcohol use, and pregnancy.

    Familial Combined Hyperlipidemia

    • Autosomal dominant inheritance; overproduction of VLDL; elevated triglycerides and cholesterol.

    Atheroma and Atherosclerosis

    • Atheroma is a lipid-rich lump in artery walls that results in atherosclerosis.
    • Pathogenesis starts with injury to blood vessels and cholesterol deposition.

    Laboratory Tests

    • Patient history, family history, physical examination, and laboratory tests are crucial for diagnosis.
    • Blood tests (e.g., cholesterol, triglycerides, HDL) are part of the assessment protocol.

    Specimen Requirements

    • Phlebotomy checks and proper sample collection procedures are critical steps, e.g., proper collection tubes (SST for biochemistry, K-EDTA for hematology).

    Laboratory Techniques (Total Cholesterol)

    • Enzymatic assay for cholesterol measurement involves three stages: cholesterol esterase, cholesterol oxidase, and hydrogen peroxide reaction with a colour reagent.

    Laboratory Techniques (Triglycerides)

    • Four-stage enzymatic assay for triglyceride measurement: lipase, glycerol kinase, glycerol phosphate oxidase, oxidation of colourless amine reagent.

    Laboratory Techniques (HDL)

    • Three-stage enzymatic assay for HDL measurement: cholesterol esterase, HDL-cholesterol oxidase, hydrogen peroxide-colour reagent reaction.

    Calculating LDL

    • Friedewald equation calculates LDL cholesterol using total cholesterol, HDL cholesterol, and triglyceride values.
    • Important to note that the Friedewald equation has limitations regarding accuracy. It is typically unsuitable for high triglyceride (>4.52 mmol/L) levels.

    Additional Tests

    • Visual inspection of serum for lipoproteins
    • Semi-routine measurement of lipoprotein A (Lp(a)) by immunoturbidimetry
    • Apoprotein analysis (e.g., Apo B, Apo A1)
    • Molecular tests for APOE and LDL receptor genetic variations.

    Treatment - Hypercholesterolaemia

    • Statins inhibit HMG-CoA reductase to lower intracellular cholesterol levels.
    • Ezetimibe inhibits cholesterol absorption.
    • Probucol has antioxidant effects on LDL.

    Treatment - Hypercholesterolaemia (other methods)

    • Nicotinic acid and derivatives inhibit fatty acid release from adipocytes and VLDL secretion.
    • Fish oil inhibits VLDL synthesis.
    • LDL apheresis removes LDL from the blood.

    Treatment – Hypertriglyceridaemia

    • Limiting fat intake (<20g/day) is a primary treatment approach.
    • Fibrates upregulate lipid metabolism-related genes, reduce triglycerides, and increase HDL levels.
    • Surgery and exercise (including gastric banding, partial gastrectomy, and intestinal bypass) can reduce triglycerides and improve lipid profiles.

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    Blood Lipids 2024-2025 Past Paper PDF

    Description

    This quiz focuses on the essential role of blood lipids in cellular structure and energy metabolism. It covers lipid biochemistry, disorders, clinical analysis, and treatment of dyslipidaemia. Students will engage with chemical structures and the clinical significance of lipid levels in health.

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