Stages of food breakdown

• Food taken into the body goes through 5 different stages during its passage through the alimentary canal (the gut):
  • Ingestion?- the taking of substances, e.g. food and drink, into the body through the mouth
  • Mechanical digestion?- the breakdown of food into smaller pieces without chemical change to the food molecules
  • Chemical digestion?- the breakdown of large, insoluble molecules into small, soluble molecules
  • Absorption?- the movement of small food molecules and ions through the wall of the intestine into the blood
  • Assimilation?- the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
  • Egestion?- the passing out of food that has not been digested or absorbed, as faeces, through the anus
• ?The role of chemical digestion is to produce small soluble molecules that can be absorbed

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