Lipid Digestion and Metabolism Quiz
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Questions and Answers

What is the primary role of lingual and gastric lipases in lipid digestion?

  • They synthesize cholesterol from fatty acids.
  • They inhibit the activity of pancreatic lipase.
  • They hydrolyze triglycerides into free fatty acids. (correct)
  • They emulsify lipids into smaller droplets.

    • What is the result of lipase activity on triglycerides as detailed in the minor digestion process?

  • Formation of phospholipids and glycerol.
  • Formation of monoglycerides and free fatty acids.
  • Formation of carbohydrates and proteins.
  • Formation of diglycerides and free fatty acids. (correct)

    • How do long chain fatty acids differ from medium chain fatty acids in terms of their carbon atom count?

  • Long chain fatty acids have 13-21 carbon atoms. (correct)
  • Long chain fatty acids have 22 or more carbon atoms.
  • Long chain fatty acids have 8-14 carbon atoms.
  • Long chain fatty acids have 4-10 carbon atoms.

    • Which type of lipoprotein is primarily involved in the transport of lipids from the intestines to other tissues?

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

    What could result from a deficiency in lipase during digestion?

    <p>Malabsorption of nutrients.</p> Signup and view all the answers

    Which enzymes are primarily responsible for major lipid digestion in the duodenum and jejunum?

    <p>Pancreatic lipolytic enzymes</p> Signup and view all the answers

    What initiates the minor digestion of triacylglycerols?

    <p>Lingual lipase and gastric lipase</p> Signup and view all the answers

    What role do bile acids play in lipid digestion?

    <p>They facilitate the formation of mixed micelles.</p> Signup and view all the answers

    What do micelles transport into the intestinal epithelial cells?

    <p>Lipolytic products</p> Signup and view all the answers

    What is the primary component of chylomicrons formed in intestinal cells?

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

    Where are bile acids synthesized?

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

    Which properties of bile salts contribute to their function in lipid digestion?

    <p>Amphipathic and detergent-like</p> Signup and view all the answers

    What substance gives bile its characteristic green color?

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

    What is the primary role of soluble fibers in cholesterol management?

    <p>Binding to bile acids and preventing their reabsorption</p> Signup and view all the answers

    Which method interrupts the enterohepatic cycle to help control high blood cholesterol?

    <p>Using soluble fibers</p> Signup and view all the answers

    Which agent is known as an NPC1L1 inhibitor used to lower cholesterol?

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

    What happens to approximately 50% of cholesterol in the ileum?

    <p>It is absorbed back into the bloodstream</p> Signup and view all the answers

    How do soluble fibers like oat bran fiber function in cholesterol reduction?

    <p>They bind to cholesterol, ensuring less absorption</p> Signup and view all the answers

    What condition is specifically mentioned as being secondary to stroke and ischemic heart disease?

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

    What is the effect of agents interrupting the enterohepatic cycle on cholesterol levels?

    <p>They lower blood cholesterol levels</p> Signup and view all the answers

    Which of the following is NOT a soluble fiber mentioned for lowering cholesterol?

    <p>Whole wheat fiber</p> Signup and view all the answers

    What is primarily responsible for the conversion of triacylglycerols to fatty acids and glycerol in capillaries?

    <p>Lipoprotein lipase</p> Signup and view all the answers

    During which processes do fatty acids enter cells following chylomicron metabolism?

    <p>They are oxidized for immediate fuel or reesterified for storage.</p> Signup and view all the answers

    How does the size of VLDL particles relate to triacylglycerol (TG) production in the liver?

    <p>Higher TG production in the liver results in larger VLDL particles.</p> Signup and view all the answers

    What key structural protein is present in VLDLs?

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

    Which component is NOT a part of chylomicrons?

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

    How do chylomicrons primarily navigate through the body?

    <p>They move through both the lymphatic system and bloodstream.</p> Signup and view all the answers

    Which statement about apoB-48 is correct in the context of chylomicrons?

    <p>ApoB-48 is present in chylomicrons.</p> Signup and view all the answers

    What role does apoC-II play in the metabolism of triacylglycerols?

    <p>It activates lipoprotein lipase for triacylglycerol conversion.</p> Signup and view all the answers

    What do VLDLs primarily transport from the liver to extrahepatic tissues?

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

    What happens to VLDLs when they encounter lipoprotein lipase?

    <p>They are hydrolyzed into IDLs.</p> Signup and view all the answers

    What is the fate of intermediate density lipoproteins (IDL) after their formation from VLDLs?

    <p>They are either taken up by the liver or converted to LDL.</p> Signup and view all the answers

    Which apolipoproteins do newly released VLDLs acquire from circulating HDLs?

    <p>Apo C and Apo E</p> Signup and view all the answers

    What is the role of ApoE in the metabolism of IDLs?

    <p>It enables binding to LDL and LRP receptors for removal from circulation.</p> Signup and view all the answers

    What is a significant competition that occurs regarding VLDL metabolism?

    <p>The metabolism of VLDLs and chylomicrons.</p> Signup and view all the answers

    What leads to the decrease in triglyceride content in IDL particles?

    <p>Hydrolysis by hepatic lipase.</p> Signup and view all the answers

    What percentage of IDL particles are typically cleared by the liver?

    <p>About 50%</p> Signup and view all the answers

    What is the primary composition of VLDLs?

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

    What occurs to IDL particles that are not taken up by the liver?

    <p>They can undergo further hydrolysis of triglycerides.</p> Signup and view all the answers

    Study Notes

    Lipid Digestion

    • Minor digestion: Lingual and gastric lipases break down medium and long chain triglycerides.
      • Long chain: 13-21 carbon atoms
      • Medium chain: 6-12 carbon atoms
      • Targets the sn-3 ester bond in Carbon 3, forming 1,2 diacylglycerol and free fatty acids
      • Important for newborn digestion of human milk.
    • Major digestion: Pancreatic lipase is responsible for the majority of lipid digestion in the duodenum and jejunum.
    • Formation of Mixed micelles: Bile acids, synthesized in the liver and stored in the gallbladder, are crucial for forming mixed micelles.
      • Bile acids are amphipathic, acting as detergents.
      • They bind to hydrophobic molecules and aid in the absorption of lipolytic products.

    Lipoprotein Metabolism

    • Chylomicrons: Transport triglycerides (TGs) from the intestines to extrahepatic tissues for storage/energy.
      • Carry cholesterol from the intestines; primarily rich in TGs.
      • Coated with Apolipoprotein B48.
    • Very Low Density Lipoproteins (VLDLs): Transport triglycerides from the liver to extrahepatic tissues for storage/energy.
      • Carry cholesterol from the liver; primarily rich in TGs.
      • Core structural protein is apoB-100.
      • VLDL synthesis occurs in the liver.
      • VLDL metabolism involves the hydrolysis of TGs by lipoprotein lipase (LPL)
    • Low Density Lipoproteins (LDLs):
      • Derived from VLDL metabolism.
      • Primarily transport cholesterol to the tissues.
      • Considered "bad cholesterol"
      • LDL Receptors: These receptors are responsible for recognizing and binding LDL particles, facilitating their uptake by cells.
      • LDL levels are primarily influenced by genetics & diet.
    • High Density Lipoproteins (HDLs):
      • Transport cholesterol from the periphery of the body back to the liver, where it can be excreted.
      • Considered "good cholesterol"
      • HDLs help remove excess cholesterol and are thought to clear plaques from arteries.

    Bile

    • Bile composition:
      • Bile acids/salts
      • Cholesterol
      • Lecithin
      • Bilirubin (gives bile its green color)
    • Enterohepatic Recycling:
      • Bile salts and cholesterol are reabsorbed in the ileum.
      • 50% of cholesterol is reabsorbed.
      • Agents that interrupt the enterohepatic cycle can be used to treat high blood cholesterol.
        • Soluble fibers (oat bran fiber, fruit pectin) bind to bile acids and/or cholesterol preventing their reabsorption.
        • Ezetimibe: an NPC1L1 inhibitor, also known as Vytorin, is a medication that blocks the absorption of cholesterol in the intestines.

    Clinical Significance

    • Obesity: Can lead to complications like stroke and ischemic heart disease.
    • Orlistat: A drug that inhibits pancreatic lipase, leading to decreased fat absorption and can be used to treat obesity.
    • Chylomicronemia: A condition characterized by high chylomicron levels in the blood. This can lead to hypertriglyceridemia and pancreatitis.
    • LDL Cholesterol: High LDL levels can contribute to atherosclerosis and cardiovascular disease.
    • HDL Cholesterol: Low HDL levels can increase the risk of cardiovascular disease.

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    Related Documents

    OS 201 Lipid Digestion & Lipoproteins PDF

    Description

    Test your knowledge on lipid digestion mechanisms and lipoprotein metabolism. This quiz covers the roles of various lipases, micelle formation, and the transport of triglycerides and cholesterol in the body. Perfect for students studying nutrition or biochemistry.

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