1 / 26

MLAB 2401: Clinical Chemistry Keri Brophy-Martinez

ama
Download Presentation

MLAB 2401: Clinical Chemistry Keri Brophy-Martinez

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. MLAB 2401: Clinical Chemistry Keri Brophy-Martinez Lipids and Lipoproteins Overview

    2. Roles of Lipids Source of energy Integral part of cellular membranes that assist in cell structure Lipids are converted to hormones or hormone precursors Insulators for nerve conduction and heat retention

    3. Types of Lipids Fatty Acids Triglyceride Phospholipids Cholesterol Cholesteryl esters

    4. Fatty Acids Linear chain of C-H bonds Terminate with a carboxyl group Body makes most fatty acids Essential fatty acids: linolenic and linoleic acid Acquired by diet

    5. Triglycerides Composed of 3 fatty acid molecules Hydrophobic Water insoluble 95% of fat stored in tissue

    6. Phospholipids Phospholipids Composed of 2 fatty acid molecules Amphipathic( having both hydrophilic and hydrophobic parts) Found on surfaces of lipid layers. Synthesized in the liver

    7. Cholesterol Cholesterol Synthesized in animals and plants Functions Promotes fat absorption in intestine Produces some hormones Transforms Vitamin D in the skin Amphipathic Found on surface on lipids

    8. Cholesterol esters Hydrophobic Located in the center of lipoproteins

    9. General Structure of Lipoproteins Size of the molecule correlates with lipid content Composed of both lipids and proteins called apolipoproteins Found on outer surface of the lipoprotein molecule

    10. Classification of Lipoproteins

    11. Classification of Lipoproteins Chylomicron Largest and least dense of the lipoproteins Lipid-rich transport vessel that carries triglyceride in circulatory system to cells VLDL: very low density lipoproteins Carry triglycerides made in liver to cells for energy needs or stored as fat

    12. Classification of Lipoproteins HDL: High density lipoproteins Gather excess cholesterol and return them to liver Made in liver and intestine LDL: Low-density lipoproteins Deliver cholesterol to peripheral cells and liver following triglyceride removal

    13. Points to Remember: lipoproteins HDL is helpful Serves to take cholesterol from the cells LDL is lethal Brings cholesterol to the cells Read from slideRead from slide

    14. Function of Apolipoproteins Maintain structural integrity Binding site for cell receptors Activator/Inhibitor of various enzymes

    15. Types of Apolipoproteins Apo A-I Major protein on HDL Apo B Principal protein on LDL, VLDL and chylomicrons Two forms: B-100 and B-48 Apo C Activates lipoprotein lipase (LPL) to break down triglycerides Apo E Promotes binding of LDL, VLDL

    16. Lipoprotein Metabolism Pathways

    17. Physiology and Metabolism Three pathways Lipid absorption Exogenous Endogenous Depend on apo-B lipoprotein particles Transport dietary lipids and hepatic-derived lipids to peripheral cells Critical transport mechanism of fatty acids to peripheral cells The fourth pathway Reverse cholesterol transport Maintains cholesterol equilibrium

    18. Lipid Absorption During digestion, pancreatic lipase cuts off fatty acids and converts dietary lipids to compounds with amphipathic properties Triglycerides, phospholipids and cholesterol esters are also transformed to amphipathic lipids These lipids form aggregates with bile acids (micelles) in the intestine

    19. Lipid Absorption Absorption occurs when micelles contact membranes of the intestinal mucosal cells Short chain fatty acids Enter circulation, picked up by albumin, taken to liver Long chain fatty acids, monoglycerides, diglycerides Re-esterified in intestinal cells to form triglycerides and cholestyl esters

    20. Exogenous Pathway Chylomicron remnants are taken up by the liver Once inside the liver, lysosomal enzymes break down the remnants to release fatty acids, free cholesterol and amino acids Some cholesterol is converted to bile acids Bile acids and free cholesterol are directly excreted into the bile, but not all exit the body Half is reabsorbed by the intestine Remainder found in stool

    22. Endogenous Pathway VLDL loses core lipids once secreted in the circulation Loss of core lipids leads to conversion of VLDL to remnants About half of the remnants are converted to LDL, and half are taken in by the liver

    24. Reverse Cholesterol Transport Pathway Mediated by HDL Excess cholesterol from peripheral cells is transported back to the liver Conversion of cholesterol into bile acids for removal

    25. Population Distribution of Lipids Concentration differs between men, women and children due to sex hormone concentration and age Women: Higher HDL Lower Cholesterol, triglyceride Aging Men and women increase in total cholesterol, LDL cholesterol and triglyceride

    26. References Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical Chemistry: Techniques, principles, Correlations. Baltimore: Wolters Kluwer Lippincott Williams & Wilkins. http://www.geekymedics.com/body-systems/metabolism/cholesterol-metabolism/ http://jimmysmithtraining.com/six-pack-diet/eggs-and-cholesterol-whats-the-truth-about-yolks http://www.healthcentral.com/diet-exercise/h/how-long-does-it-take-for-polyunsaturated-fatty-acid-to-work.html http://www.medicine-raw-materials.com/others/page_8.html Sunheimer, R., & Graves, L. (2010). Clinical Laboratory Chemistry. Upper Saddle River: Pearson .

More Related