Absorption of monoglycerides & fatty acids

• What do micelles do?

  Micelles transport fatty acids and monoglycerides to the epithelial cell membrane.
• What are micelles made up of?

  • Bile salts (which are hydrophobic & hydrophilic)
  • Monoglycerides & fatty acids (which are hydrophobic)
• Why are micelles needed to transport monoglycerides and fatty acids to the epithelial cell membrane?

  Because monoglycerides and fatty acids are hydrophobic and so will repel water.
• How do monoglycerides and fatty acids enter the epithelial cell membrane?

  They exit the micelle near the cell membrane and diffuse through it.
• Why can monoglycerides and fatty acids move through the cell membrane by simple diffusion?

  Because they are lipid soluble and small.
• What do monoglycerides and fatty acids do in the smooth ER in the epithelial cell?

  They recombine to form triglycerides.
• What happens to the triglycerides in the golgi body?

  They are associated with cholesterol and lipoproteins to form chylomicrons.
• What are chylomicrons?

  Large structures which move triglycerides around the body.
• How do chylomicrons leave the epithelial cell?

  Via exocytosis.
• Where do chylomicrons go once they have left the epithelial cell?

  They enter the lacteal.
• What does the lacteal link to?

  The lymphatic system
• How does the chylomicron leave the lymphatic system and enter the blood?

  Exits through the thoracic duct and into the subclavian vein.
• What are micelles?

  • Water soluble vesicles formed from fatty acids, glycerol, monoglycerides and bile salts
• How does lipid absorption work?

  • Micelles deliver fatty acids, glycerol and monoglycerides to epithelial cells of ileum for absorption
  • cross via simple diffusion as lipid-soluble and non-polar
• How and where are lipids modified in the cell?

  • Smooth ER reforms monoglycerides / fatty acids into triglycerides
  • golgi apparatus combines triglycerides with proteins to form vesicles called chylomicrons
• How do lipids enter the blood after modification?

  • Chylomicrons move out of cell via exocytosis and enter lacteal
  • lymphatic vessels carry chylomicrons and deposit them in bloodstream