Enzymes and Digestion

• Enzymes


  Produced by cells and then released into the gut to mix with food
• Digestive enzymes


  • Break down big molecules like starch, proteins and fats into smaller, soluble molecules like sugars, amino acids, glycerol and fatty acids
  • Allow the smaller molecules to pass through the walls of the digestive system and be absorbed into the bloodstream
• Carbohydrases


  Convert carbohydrates into simple sugars
• Carbohydrase


  • Amylase
• Amylase


  Breaks down starch
• Places where amylase is made

  • Salivary glands
  • Pancreas
  • Small intestine
• Proteases


  Convert proteins into amino acids
• Places where proteases are made

  • Stomach (pepsin)
  • Pancreas
  • Small intestine
• Lipases


  Convert lipids into glycerol and fatty acids
• Places where lipases are made

  • Pancreas
  • Small intestine
• The body makes good use of the products of digestion to make new carbohydrates, proteins and lipids. Some of the glucose is used in respiration.
• Bile


  Neutralises the stomach acid and emulsifies fats
• Functions of bile


  • Neutralises the acidic pH in the stomach
  • Emulsifies fats to increase the surface area for lipase to work on
• Bile is produced in the liver and stored in the gall bladder before being released into the small intestine.
• Enzymes used in the digestive system are produced by specialised cells in glands and in the gut lining
• Different enzymes


  Catalyse the breakdown of different food molecules
• Tongue


  • Salivary glands produce amylase enzyme in the saliva
• Liver


  • Produces bile
  • Bile neutralises stomach acid and emulsifies fats
• Stomach


  • Pummels the food with its muscular walls
  • Produces the protease enzyme, pepsin
  • Produces hydrochloric acid to kill bacteria and provide the right pH for protease enzyme to work (pH 2-acidic)
• Gall bladder


  • Stores bile before it's released into the small intestine
• Pancreas


  • Produces protease, amylase and lipase enzymes
  • Releases these enzymes into the small intestine
• Small intestine


  • Produces protease, amylase and lipase enzymes to complete digestion
  • Where the digested food is absorbed out of the digestive system into the blood
• Large intestine


  • Where excess water is absorbed from the food
• Rectum


  • Where the faeces (made up mainly of indigestible food) are stored before they bid you a fond farewell through the anus