Nutrition

• Digestion in the mouth

  1. Mechanical digestion by teeth

  2. Mucus added for lubrication

  3. Moved along to stomach by peristalsis
• Digestion in the stomach

  1. HCl destroys pathogens

  2. Stomach churns food to further mechanically digest
• Digestion in the duodenum

  1. Bile and secretions from Brunner's glands neutralise stomach acid

  2. Pancreatic amylase hydrolyses remaining starch to maltose
• Digestion in the ileum

  1. Epithelial cells hydrolyse disaccharides into monosaccharides

  2. Absorbed into epithelial cells

  3. Water, mineral ions and vitamins absorbed
• Digestion in the colon

  Indigestible food, undigested cellulose, sloughed off cells and bacteria stored and then egested
• Carbohydrate digestion


  • Starch digestion destroyed by salivary amylase
  • Disaccharides hydrolysed into monosaccharides and absorbed
• Protein digestion


  • Polypeptides hydrolysed into amino acids by exopeptidases
  • Absorbed into epithelial cells then blood
• Lipid digestion


  • Bile salts emulsify lipids
  • Lipids absorbed into lymphatic system
• Water, mineral ions and vitamins are absorbed
• Indigestible food, undigested cellulose, sloughed off cells and bacteria are stored and then egested