Chemical Digestion
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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