Digestion

• The process of breaking down food into simpler substances so they can pass into the bloodstream and provide nutrients and energy to our body is called digestion
• Mechanical Digestion: Food is physically broken down into smaller pieces by teeth and by churning muscles in the stomach
• Chemical Digestion:

  • Enzymes break complex molecules into simpler substances
  • Occurs at several stages along the gut
• Oesophagus

  • 25 cm tube connecting mouth with stomach
  • Muscles push ball of food down by contracting behind ball
  • Flap of skin at top of windpipe blocks windpipe when we swallow
  • Circle of muscles separate oesophagus from stomach
• Stomach

  • J shaped organ that has capacity of about 2L
  • Muscles in stomach churn food
  • Walls of stomach release gastric juices
• Gastric Juice Contains 3 Substances

  1. Pepsin which breaks down proteins
  2. Hydrochloric Acid which kills harmful bacteria
  3. Mucus which lines and protects stomach from enzymes and acid
• Pancreas

  • Not a part of gut but a 15cm side attachment
  • Produces pancreatic juice
• Pancreatic Juice Contains 3 Substances

  1. Enzymes to digest carbs, fats and proteins
  2. Insulin controls amount of sugar in bloodstream
  3. Base to neutralise acid in chyme that came from stomach
• Gall Bladder

  • Stores bile produced by liver
  • Bile is used to break down fats
• The Liver

  • Over 500 chemical processes take place