The Digestive System

Foods that we consume are sources of nutrients and these nutrients are released and utilised in the body through the processes involved in digestion. It is therefore important to first look the digestive system to build your understanding of nutrition.

The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat, our body has to break the food down into smaller molecules that it can process; it also has to excrete waste.

In terms of their nutrition, humans are defined as being heterotrophs (heteros = different, troph = feeding). This means humans take in large complex organic molecules and then break them down into their smallest components which are absorbed and then made into large molecules again.


Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body.

The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals.

Main sections of the alimentary canal

  • mouth
  • oesophagus
  • stomach
  • duodenum
  • ileum
  • pancreas
  • liver
  • colon
  • rectum and anus


The Alimentary Canal or Gastrointestinal Tract (G.I.T)




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