The Digestive System

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• [Image: http://www.jewishhealthzone.com/wp-content/uploads/2011/11/Diagram-of-the-Digestive-System.jpg]

1. Mouth
   1. Where food is mixed and chewed with saliva
   2. Enzyme called Amylase begins the breakdown of starch
2. Oesophagus
   1. tube that carries food to the stomach by muscular action
3. Liver
   1. produces bile which helps to breakdown fats
4. Small Intestine
   1. food molecules are absorbed into bloodstream
      1. after final breakdown by enzymes
5. Large Intestine
   1. passes water back into the blood leaving solid waste
6. Stomach
   1. stores food and mixes it with digestive juices
   2. makes acid to kill bacteria
7. Pancreas
   1. produces more digestive enzymes

1. Ingestion
   1. taking food into the mouth
2. Digestion
   1. breaking down of food into its molecules
   2. physical/chemical
3. Absorption
   1. passing of the food molecules through the walls of the small intestine and into the bloodstream
4. Assimilation
   1. body cells take in the food molecules from the blood
      1. cells use food molecules for energy, growth and repair
5. Egestion
   1. undigested food is passed out of the body
      1. e.g. Fibre

1. Chemical
   1. second stage of digestion
   2. enzymes
      1. made in mouth, stomach, pancreas and small intestine
      2. catalysts
   3. An Enzyme is a chemical, made in a living cell, which can speed up a chemical reaction, without itself being changed
   4. substrate
      1. substance enzyme acts on
   5. product
      1. broken down substrate
2. Phyical
   1. first stage of digestion
   2. breaking down of food into smaller pieces in the mouth
   3. teeth

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      • [Image: http://www.gtchild.co.uk/content/images/stories/human_body/teeth_mouth.jpg]
      1. incisors
         1. sharp teeth at front of mouth
         2. used to cut food
      2. canines
         1. pointed teeth which tear food
      3. premolars
         1. flat teeth used to grind food
      4. molars
         1. large, flat teeth at the back
         2. also used for grinding

1. Starch
   1. carbohydrate made up of long chains of glucose molecules linked together
   2. broken down in the mouth and small intestine by an enzyme called amylase
2. Amylase
   1. breaks down starch into many molecules of a sugar called maltose
   2. enzyme
3. Maltase
   1. enzyme
   2. acts on maltose molecules breaking them down into single glucose molecules
4. glucose molecules
   1. final breakdown products of starch
   2. small enough to be absorbed into blood
      1. through wall of small intestine