Digestion and absorption of lipids

Cards (34)

  • What is the role of digestive enzymes in digestion?
    They facilitate hydrolytic cleavage of molecules
  • What are triglycerides composed of?
    3 fatty acids esterified to 1 glycerol
  • Why are lipids significant in terms of energy yield?
    They yield more energy when oxidized
  • Where does lipid digestion occur?
    • Mouth
    • Stomach
    • Small Intestine
  • What initiates lipid digestion in the mouth?
    Mastication and emulsification of lipids
  • What enzyme in saliva aids lipid digestion?
    Lingual lipase
  • What type of enzyme is lingual lipase?
    It is a serine protease
  • What does lingual lipase hydrolyze?
    Medium and long-chain triglycerides
  • What are the products of lipid digestion in the mouth?
    Diglycerides, monoglycerides, and fatty acids
  • Which enzymes act on lipids in the stomach?
    Lingual lipase and gastric lipase
  • What is the role of gastric lipase?
    It hydrolyzes ester bonds in triglycerides
  • What type of enzymes are both lingual and gastric lipases?
    Serine proteases
  • What happens to lipids in the small intestine?
    Mechanical digestion and emulsification continue
  • How is the surface area of lipid droplets increased in the small intestine?
    Through peristalsis and bile salts
  • What does the pancreas secrete for lipid digestion?
    Pancreatic lipase and pancreatic co-lipase
  • What is the function of pancreatic lipase?
    It hydrolyzes triglycerides to monoacylglycerol and fatty acids
  • How does the lipase co-lipase complex function?
    It spreads over the surface of lipid droplets
  • What does cholesterol esterase do?
    Hydrolyzes cholesteryl esters to cholesterol
  • What is the role of phospholipase A2?
    It digests phospholipids to lyso-phospholipid
  • What activates phospholipase A2?
    Trypsin
  • What is required for optimum activity of phospholipase A2?
    Bile salts
  • What does lysophospholipase do?
    Removes remaining fatty acid at C1
  • What are the primary products of lipid digestion?
    Free fatty acids, free cholesterol, 2-monoacylglycerol
  • What forms the mixed micelles in lipid digestion?
    • Bile salts
    • Free fatty acids
    • Free cholesterol
    • 2-monoacylglycerol
    • Phospholipid
  • How do micelles facilitate lipid absorption?
    They transport hydrophobic lipids across water layers
  • What do short-medium chain fatty acids require for absorption?
    They do not require mixed micelles
  • What happens to fatty acids and monoglycerides in enterocytes?
    They are used to synthesize triglycerides
  • What are chylomicrons composed of?
    Triglycerides, cholesterol esters, free cholesterol
  • What happens to chylomicrons after formation?
    They move to the Golgi apparatus
  • How are chylomicrons released from enterocytes?
    Through exocytosis into the extracellular space
  • What factors are essential for normal lipid absorption?
    Bile salts, normal pancreatic function, intestinal cells
  • What percentage of dietary fat is utilized?
    95%
  • Which nutrients are not digested?
    Keratins and plant polymers like cellulose
  • What do some vegetables contain that is indigestible?
    Indigestible carbohydrates