Excretion Facts



  • Digestive excretion is the way your body gets rid of food that it cannot digest.
  • Undigested food is prepared for excretion in your large intestine or bowel.
  • The main part of the large intestine is the colon, which is al most as long as you are tall.
  • The colon converts the semi-liquid ‘chyme’ (see digestion) of undigested food into solid waste, by absorbing water.
  • The colon soaks up 1.5 liters of water every day.
  • The colon walls also absorb sodium and chlorine and get rid of bicarbonate and potassium.
  • Billions of bacteria live inside the colon and help turn the chyme into faeces. These bacteria are harmless as long as they do not spread to the rest of the body.
  • Bacteria in the colon make vitamins K and B – as well as smelly gases such as methane and hydrogen sulphide.
  • The muscles of the colon break the waste food down into segments ready for excretion.