DIGESTION

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•        Tongue mixes food with saliva.
•        Teeth breaks up food.
•        Oesophagus carries food into the stomach.
•        Liver produces a variety of substances, including bile( for breaking down fatty foods).
•         Gall bladder stores bile.
•        Stomach mixes the food with digestive juices.
•        Pancreas sends enzymes to the small intestine.
•        Small intestine lets liquid food into the bloodstream.
•        Large intestine extracts water and carries away waste.
•        Appendix has no useful purpose.
•        Rectum is the final part of the large intestine.
•        Anus lets waste pass out of the body.

After food has been broken into small pieces by the teeth, glands in the mouth add saliva to soften it. Saliva also contains an enzyme which changes starch  to sugar. The food is then swallowed, and enters the digestive system known as the alimentary canal. Muscular walls push food down the oesophagus, or gullet. A valve leta food into the stomach. Here it is mixed with acid, enzymes and mucus produced by cells in tiny glands in the stomach lining.

In the stomach, food is constantly churned up with digestive juices to make a porridge- like mixture called chime. When this is ready to leave the stomach, a valve opens and food is squeezed out into the small intestine. Here more digestive juices are added- Enzymes from the pancreas and small intestine, and bile from the gall bladder in the liver.

The small intestine has thin walls with finger- like projections called villi. Liquid food passes through these into the blood in the capillaries. Waste material does not pass through.

Cellulose from plants such as cabbage is necessary for roughage, but because it cannot be digested, it is passed on along with some water into the large intestine. There, water is taken back into the blood, and solid waste is carried away to be expelled through the anus.