THE HUMAN DIGESTIVE SYSTEM

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THE HUMAN DIGESTIVE SYSTEM

• The journey of food

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OB6

• identify and locate the major parts of the
  digestive system including the mouth, oesophagus,
  stomach,liver, pancreas, small intestine and
  large intestine, and know their functions

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The Mouth.

• Teeth break down food into small pieces.
• Salivary glands make saliva.
• Chewed food gets mixed with saliva.
• Saliva contains enzymes, which start to digest
  starch to sugar.

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The Oesophagus.

• Passes food down to your stomach.
• The oesophagus has circular muscles in its wall.
• These muscles contract and squeeze in behind the
  food to push it along.

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The Stomach

• Muscular bag that holds 2 litres of food.
• Secretes hydrochloric acid.
• Makes digestive juices.
• Muscular walls churn the food making sure its
  all mixed.
• After 2-3 hours churning its a runny liquid.

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The Small Intestine

• Actually 6 m long!
• Plays important roles in digestion and absorption
• Two important liquids are added here
• Pancreatic juices
• Bile

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Absorption

• Digested food has to pass into the blood through
  the gut wall.
• Well designed thin lining, good blood supply
  and a VERY LARGE surface area.
• It has a folded inner lining, millions of tiny
  villi

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Pancreas

• Produces digestive enzymes
• E.g. amylase

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Liver

• After food has been absorbed into the blood, the
  food is taken to the liver.
• The liver processes some of it, before it goes
  any further.
• The food dissolved in plasma is the taken to
  other parts of the body.

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The Large Intestine.

• Mainly fibre, dead cell, bacteria and water reach
  here!
• As it moves along here most of the water is
  absorbed into the blood.
• Faeces are stored in the rectum.
• Eventually egested out of the anus, roughly 24
  48 hours after eating.

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