The alimentary canal - about nine metres long, starting at the mouth and ending at the anus.
The accessory organs which assist with digestion, absorption and storage of food substances. These are the pancreas, liver and gall bladder.
Protein foods are broken down into amino-acids by pepsin in the stomach.
Excess amino acids are broken down into glucose and urea. Glucose is used as fuel and urea is excreted by the kidneys.
It converts fat which is stored in the body into a suitable form for combustion.
It stores iron and Vitamins A, B12, D, E and K.
Diarrhoea, sometimes due to food poisoning, can result in dehydration.
It forms Vitamin A from carotene.