Part 7
Anatomy
The Digestive System F
ood provides the energy necessary for life, but when food first enters the body, it is in a form that the cells of the body cannot use. Therefore, the body must break it down into small molecules which can pass through the lining of the bowel, through the blood vessel walls, and, finally, through the walls of the cells to where the energy is needed. The process of breaking down food into fuel that the body can use is known as digestion, and the parts of the body which bring this about are collectively known as the digestive system. The digestive system is made up of: • The mouth, pharynx and oesophagus • The stomach • The small intestine • The large intestine • The rectum and anus • The liver • The pancreas
THE MOUTH, PHARYNX AND OESOPHAGUS The system starts with the lips and muzzle, which select the food to be eaten. The food is then bitten off (in the case of grass and long-stemmed hay) or taken in by the incisor teeth. From here, the tongue pushes the food back to the molar teeth, where it is ground up and mixed with saliva.
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