Major parts of digestive systems

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  • Created by: Jasmin
  • Created on: 01-12-13 19:14
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  • Major parts of the Digestive System
    • Mouth
      • Teeth break down food and tongue pushes food down oesophagus
        • Saliva is secreted to make food easier to swallow and contains enzymes which start the chemical digestion process
    • Oesophagus
      • Take food from mouth to stomach using waves of muscular contractions called peristalsis
        • Mucus is secreted from tissues of walls to lubricate the food's passage downwards
          • Thick muscular wall
    • Stomach
      • Muscular sac, inner layer produces enzymes
        • Entrance and exit of stomach are controlled by sphincter muscles
          • Role is to store and break down food, esp proteins
            • Stomach walls produce gastric juice, helps break food down
              • Gastric juice consists of HCL, pepsin (enzyme) and mucus
                • Mucus prevents the stomach being digested by its own enzymes
                  • Peristalsis of stomach turns food into acidic fluid - chyme
    • Small Intestine
      • Long muscular tube
        • Chyme is moved along SI by peristalsis
          • Duodenum: bile (alkaline) and pancreatic juice neturalise the acidity of chime and break it down into smaller molecules
            • Ileum: small soluble molecules are absorbed through villi that line the gut wall
              • Villi increase SA for absorption into the bloodstream
    • Large Intestine
      • a.k.a colon
        • Absorbs water, salts and minerals
          • Has folded wall - large SA for absorption
            • Food becomes drier and thicker to form faeces
    • Rectum
      • Faeces stored here
        • Pass through sphincter muscles to anus is process called egestion or defecation
    • Glands
      • Salivary Glands
        • Secrete saliva - consists of mucus, mineral salts, salivary amylase
          • Salivary amylase breaks down starch into maltose
      • Pancreas
        • Releases pancreatic juice into duodenum through pancreatic duct
          • Contains proteases to digest protein, lipase for lipids and amylase to digest starch
            • Contains sodium hydrogen carbonate which neutralises the acidity of HCL acid from the stomach


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