Stages of digestion

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  • Created by: Katy **
  • Created on: 31-12-13 10:53

Stage 1 - Mouth

  • Digestion starts with the mechanical digestion by the teeth in the mouth.
  • Then a chemical digestion by saliva starts - carbohydrase digests glusoce
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Step 2 - Oesophagus

  • This is a muscular tube (gullet).
  • When you swallow, the food moves to the stomach.
  • The food moves by involentary contractions (peristalsis).
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Step 3. - Pancreas & Stomach

  • pH of 2-3
  • The pancrease will secrete enzymes - lipase, protease & carbohydrase.
  • The stomach will secrete hydrochloric acid that will digest bacteria.
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Step 4. - Small Intestine

  • The rest of the enzyme carbohydrase will digest starch into glucose.
  • Protease will digest protein to amino acids.
  • Lipase will digest fats into fatty acids & glycerol.
  • The food molecules have to be small enough to be absorbed throught the wall of the small intestine & into the blood.
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Step 5. - Large Instestine

  • The water is reabsorbed into the blood.
  • Fibre is insoluble & cannot be digested, this is why it is stored & then egested through the ****.

egested - pushed out

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Bile & Liver

  • Liver produces bile (chemical).
  • Bile is stored in the gall bladder
  • Bile has 2 functions - neutralise stomach acid & produce alkaline conditions for enzymes to work in
  • Emulisification converts large fat globules to smaller fat droplets
  • The enzymes produced by the body help digestion.
  • Everything that is digested is absorbed into the blood.
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