The Digestion Process
Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules.
Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine. In the mouth, food is chewed up and mixed with saliva to prepare for the journey to the stomach. Enzymes in saliva begin to break down the structure of foods.
The Digestive System
- Oesophagus
- - Food and liquids travel down oesophagus to stomach through process of peristalsis (wavelike contractions and relaxations of the oesophagus wall).
- Stomach
- - The lining of the stomach produces acid and an enzyme that digests protein. The acid in your stomach lowers the pH level so that some enzymes can start to break down food.
- Small Intestine
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- When food leaves the stomach it begins moving through the small intestine, where digestive juices from the liver, pancreas and intestinal wall contribute to the breakdown of foods and release of nutrients.
Most digested molecules of food, as well as water and minerals, are absorbed through the lining of the small intestine, where they enter the bloodstream to be supplied as nutrients to the cells of the body.
- Large Intestine
- Undigested food moves from the small intestine to the large intestine, where it is prepared for expulsion from the body as waste via the colon.
During passage through the large intestine, water and any remaining nutrients are absorbed through the intestinal wall.