The Digestive System

The Digestive System

1. Digestion Stages

   • 1. Ingestion - the taking in of substances (eg food and drink) into the body through the mouth
     • 2. Mechanical Digestion - the breakdown of food into smaller pieces without chemical change to the food
       • 3. Chemical Digestion - the breakdown of large insoluble molecules into small, soluble molecules
         • 4. Absorption - the movement of small food molecules and ion's through the wall of the intestine into the blood
           • 5.Assimilation - the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
             • 6. Egestion - the passing out of food that has been digested or absorbed as faeces, through the anus
       • Teeth
         • Incisors are in the front of the jaw, there are 4 on the top and 4 on the bottom
         • Canines are behind the incisors, there are 2 on top and 2 on the bottom
         • Premolars are behind the canines, there are 4 on top and 4 on the bottom
         • Molars are at the back of the mouth and there are 4 on the bottom and 4 on the top
         • Tooth Decay
           • Bacteria on teeth use sugar to survive
             • Bacteria produce a sticky matrix which traps food particles and forms a plaque coating around the teeth
               • Sugars are converted to acids by the bacteria
                 • The acids remove calcium and phosphate from the enamel and are able to reach the dentine
           • Tooth Decay Prevention
             • To prevent tooth decay you need to...
               • Eat food with a low sugar content
               • Regularly brush your teeth effectively

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