Humans nutrition

• Endopeptidases


  Proteases that hydrolyse peptide bonds between specific amino acids in the middle of the polypeptide chain to form shorter polypeptide chains
• Exopeptidases


  Proteases that hydrolyse peptide bonds on the end of peptides, from the free amino end or the free carboxyl end
• Exopeptidases hydrolise bonds on the end of peptides from the free...


  amino end or carboxyl end
• Buccal cavity – mechanical digestion of food occurs here. The tongue moves food to the cutting and grinding surfaces of the teeth. Chemical digestion of starch and glycogen into maltose by the enzyme amylase. Saliva moistens food and also maintains the pH for the enzyme. The tongue then rolls the food into a bolus which is swallowed.
• Liver – produces bile. Bile emulsifies lipids to increase the surface area available for lipase enzymes to digest them. It also neutralises stomach acid to create a slightly alkaline pH in the duodenum for the pancreatic enzymes.
• Gall bladder – stores the bile before delivering it to the duodenum via the bile duct.
• Pancreas – produces enzymes that are transported to the duodenum via the pancreatic duct. Carbohydrase - pancreatic amylase.
• Stomach – gastric glands in the mucosa produce gastric juice. The Oxyntic cells produce hydrochloric acid (HCl) that kills bacteria and lowers the pH to 2. The chief or peptic cells produce pepsinogen, the inactive precursor of the endopeptidase enzyme, pepsin. This is activated by the HCl. Finally, the goblet cells produce mucus to protect the stomach lining.
• Oesophagus – Peristalsis waves of muscle contraction push the bolus of food down to the stomach. Mucus lubricates the way.