digestion system

• The Mouth

  • Teeth CHEW the food
  • SALIVARY GLANDS in the mouth secrete AMYLASE in saliva to begin to break down starch from the food into maltose.
• Oesophagus

  • A tube that connects the mouth to the stomach
• The Stomach

  • Has muscular walls that churn food into smaller pieces
  • It produces PEPSIN, a type of protease enzyme to break down PROTEINS
  • It produces HYDROCHLORIC ACID to KILL BACTERIA and to provide the optimum pH for the pepsin to work in
• The Liver

  • Produces BILE, crucial for NEUTRALISING stomach acid and EMULSIFYING FATS into smaller droplets so they can be more easily digested by lipase enzymes.
  • The bile is STORED in the GALL BLADDER and released into the SMALL INTESTINE.
• The Pancreas

  • It produces PROTEASE, AMYLASE, and LIPASE.
• The Small Intestine

  • Produces PROTEASE, AMYLASE, and LIPASE.
  • Amylase digests starch into maltose
  • Protease digests proteins into amino acids
  • Lipase digests lipids into fatty acids and glycerol
  • This is where digestion is completed, where the broken down nutrients are ABSORBED through specialised intestinal walls into the bloodstream.
• The Large Intestine

  • The large intestine absorbs EXCESS WATER from digested food.
  • Waste is eventually moved to the RECTUM as faeces and exits the body through the ANUS.
• DIGESTIVE ORDER:

  1. MOUTH
  2. OESOPHAGUS
• DIGESTIVE ORDER:

  1. MOUTH
  2. OESOPHAGUS
  3. STOMACH
  4. LIVER
  5. PANCREAS
  6. SMALL INTESTINE
  7. LARGE INTESTINE (rectum and anus)

  ACRONYM: My Older Sister Lilia Poos Small Lice
• Testing for Starch: IODINE SOLUTION


  • Place the sample in a test tube and add iodine solution.
  • A colour change from BROWN-ORANGE to BLUE-BLACK signifies the presence of starch.
• Testing for Sugars: BENEDICTS REAGENT

  1. Add the food sample to a test tube, mix in Benedict's solution.
  2. Heat the tube in a WATER BATH for 5 minutes at 75°C.
  3. A colour change indicates the presence of reducing sugars, with the colour varying from BLUE to GREEN to YELLOW or BRICK-RED depending on sugar concentration.
• Testing for Proteins: BIURET SOLUTION


  1. Combine the food sample with Biuret solution in a test tube.
  2. Gently shake; a change to PURPLE indicates protein. If no protein, the solution remains BLUE.
• Testing for Lipids: ETHANOL TEST

  1. Add a few drops of ethanol and a few drops of distilled water to a test tube containing the prepared food sample.
  2.  Shake gently to mix the contents of the test tube.
  3. If a lipid is present in the sample, the colourless solution will turn into a cloudy white emulsion.