Human Alimentary Canal: Structure & Function ( Edexcel IGCSE Biology )

The human digestive system includes the organs of the alimentary canal and accessory organs that work together to break large insoluble molecules into small soluble molecules

Alimentary canal and accessory structures table

The Stages of Food Breakdown

• Food taken into the body goes through six different stages during its passage through the alimentary canal (the gut):
  • Ingestion - the taking in 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