The digestive system

• Digestive system


  • The route consumed material follows into and out of your body
  • Large molecules are broken down into particles that can move into the blood stream to be used by cells
• What does food supply?

  The nutrients needed for growth and repair of the body
• What is the digestive system responsible for?

  Breaking down food from the environment for small particles to enter the circulatory system and become part of organism
• What do your teeth do?

  • Chew food into smaller particles
  • This increases the surface area on which enzymes can work upon
• What enzyme is in your mouth?

  • Salivary amylase which is a carbohydrase
  • Produced by your saliva gland
  • It's role is to break down large carbohydrates into smaller molecules
• Food track to digestive system

  • It enters through your moth where your teeth chew down the food into smaller molecules and salivary amaylase breaks down glucose molecules
  • It passes through your oesophagus into your stomach which is a muscular bag which is lined with special cells producing hydrochloric acid .
• Hydrochloric acid roles

  • Provide the correct pH levels for stomach protease
  • Helps digest food further into smaller molecules
  • To sterilise food and remove any dangerous microbes
• Protease

  • Enzymes that break down proteins into their amino acids
  • The protease in the stomach is special as it works at an acidic pH
• How is food poising formed?

  When hydrochloric acid in your stomach fails to sterilise food
• How often are cells in your stomach replaced and why?

  Every 3 days because the acid is strong and can harm cells
• Bile properties

  • Alkaline
  • Neutralises stomach acids
  • This allows enzymes produced by the pancreas to work
  • Causes fats to from tiny globules so they can disperse in water and make an emulsion
• What does high pH of stomach acids cause

  • It destroys pancreatic enzymes
• What does the pancreases produce?


  • Enzymes to act in the small intestine
• Food in the stomach and liver


  • Main digestion processes occur in the stomach and small intestine
  • The food in the stomach is churned for between 2-5 hours depending on the size of the meal and what it consisted of
  • The food then moves into the small intestine where bile from liver and enzymes from pancreas decrease the size
  • Food is broken down as it needs to pass through the enzyme wall into the circulatory system
• Products of digestion

  • Amino acids
  • Fatty acids and glycerol
  • Sugars/glucose
  • If the products are small enough, they are absorbed into the capillaries of the villi
  • The small intestine has a large surface area to maximise the area for absorption
• What happens to undigested food?

  • After 5-6 hours, Undigested food passes through the large intestine
  • Here water is reabsorbed from the mass
  • Once the water has been removed the remaining mass is called the faeces and it's stored in rectum until egestion
• Egestion


  • When the anal sphincter is opened and the faeces leaves the body