Digestion and Absorption

    Cards (6)

    • Large molecules are hydrolysed into smaller molecules
    • Digestion of Carbohydrates:
      • Begins in mouth, then duodenum, then completed in the ileum
      • Involves amylase and membrane-bound disaccharidases
      • Amylases produced in the salivary glands and pancreas, hydrolysing polypeptides into maltose, breaking glycosidic bonds
      • Sucrase and Lactase are membrane-bound enzymes
    • DIgestion of Proteins:
      • Begins in the stomach, then duodenum, then ends in ileum
      • Endopeptidases hydrolyse peptide bonds in the middle
      • Exopeptidases hydrolyse peptide bonds at the ends
      • Membrane Bound Peptidases hydrolyse peptide bonds between 2 amino acids
    • Digestion of Lipids:
      • Digested by lipase and bile salts
      • Lipase is produced in the pancreas, hydrolysing ester bonds in triglycerides to form monoglycerides and fatty acids
      • Bile salts produced in the liver emulsify lipids into micelles to increase surface area for lipase to act on
      • Micelles include fatty acids, glycerol, monoglycerides and bile salts
      • Micelles are non-polar and can simply diffuse across membranes
      • Micelles are modified back into triglycerides in the golgi and ER once in the cell
    • Absorption occurs in the ileum, walls are covered in villi and microvilli to increase surface area, with a network of capillaries to reduce diffusion distance
    • Glucose and Amino Acids require active transport and co-transport to be absorbed as there is a higher concentration in the epithelial cell