Enzymes and Digestion

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  • Created by: Jasmin
  • Created on: 19-10-13 16:42
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  • Enzymes and Digestion
    • MOUTH
      • Salivary Amylase = Starch (poly)--> Maltose (dis) (incomplete)
      • Process of chewing (mastication) provides large SA and mixing of components of saliva with food
      • Pepsinogen = Protein (poly) --> Amino acids
        • Pepsinogen activated in stomach by presence of HCL
      • pH 1/2
        • Low pH not activity of amylase in stomach
        • Acidic conditions provide optimum environment for proteases that digest proteins
        • HCL acid secreted from lining of stomach cells
          • Acidity helps kill bacteria
            • Acidic conditions can harm stomach so mucus is secreted to provide protective lining from specialised cells - goblet cells
      • After digestion and muscular contractions of stomach wall chime is produced
        • Passed through pyloric sphincter into duodenum
          • All juices secreted make gastric juice secreted from gastric pits
      • Pancreatic Amylase = Maltose (dis) --> Alpha glucose (mono). Sucrose (dis)--> Alpha glucose, fructose (mono) does not require digestion. Starch --> Maltose pH7
      • Lipase = lipids --> fatty acid and glycerol
        • Bile helps to emulsify lipids by breaking them up into tinny droplets for easy digestion
      • Protease = proteins (poly) --> Amino acids
      • Bile made in liver, stored in gall bladder
        • Contains bile salts
          • Help raise/neutralise pH
        • Bile is secreted into duodenum via bile duct and mixed with food
      • Pancreatic juice secreted into dudoenum
        • Contains a mixture of enzymes - protease, lipase and carbohydrase and alkaline salts
          • Raise pH
            • So optimum pH is reached for activity of enzymes
      • Absorption of water from faeces
      • Mucosa of ileum folded to form villi
        • Microvilli
          • Large SA for digestion and absorption
    • Hydrolysis
      • Splitting up of molecules by adding water to the chemical bonds that hold them together
    • Maltose Lactose Sucrose (dis) does require digestion
    • Starch Requires digestion
    • Cellulose (poly) indigestible in humans


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