Digestion and absorption

• proteins digested in the human gut as

  
  

  1. Hydrolysis of peptide bonds

  2. Endo peptidases break polypeptides into smaller peptide chains (middle of polypeptide chains)

  3. Exo peptidases remove/ break terminal (end) amino acids

  4. Di peptidases hydrolyse dipeptides into amino acids.
• digestion of lipids

  -emulsified by bile salts produced by the liver

  this breaks down large fat soluble molecules into micelles increasing surface area

  • Lipase hydrolyses the ester bond between the monoglycerides and fatty acids.
• absorption of lipids:

  
  

  1. Micelles contain bile salts and fatty acids
  2. release fatty acids to cell lining of the ileum
  3. Fatty acids are absorbed by diffusion
  4. chylomicrons form
  5. Vesicles move to cell membrane
• Role of Golgi apparatus in lipid digestion

  • Golgi (apparatus)
  • Modifies / processes triglycerides;
  • Combines triglycerides with proteins;
  • Packaged for release / exocytosis
• advantage of lipid droplets in digestion

  •  Droplets increase surface areas for lipase action
  • So faster hydrolysis / digestion of triglycerides / lipids
• importance of micelles in lipid digestion

  • Micelles carry fatty acids and glycerol / monoglycerides through membrane to cells
• Describe role of micelles in the absorbption of fats into the cells lining of ileum

  • Micelles include bile salts and fatty acids and monoglycerides
  • make the fatty acids more soluble in water
  • bring / release fatty acids to lining of the ileum
  • this maintains a higher concentration of fatty acids to the lining of the ileum
  • fatty acids absorbed by diffusion