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THE HUMAN DIGESTIVE SYSTEM

THE HUMAN DIGESTIVE SYSTEM. The journey of food. 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. The Mouth. Teeth break down food into small pieces.

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THE HUMAN DIGESTIVE SYSTEM

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  1. THE HUMAN DIGESTIVE SYSTEM The journey of food

  2. 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

  3. 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.

  4. Teeth. • Four Types • Incisors - Cutting • Canine – Grip and tearing • Molars and Pre-Molars for grinding Notes on next page

  5. There are four types of teeth cut and slice through food Incisors Canines grip and tear food Premolars chew and crush food chew and crush food Molars

  6. Teeth. • Enamel- Hard outer layer • Dentine – Softer interior • Plaque - Bacteria that attack the teeth

  7. Digestion -Breaking food down into smaller pieces Saliva contains an ENZYME (Amylase) Teeth begin process of breaking down food Food Shorter sugars that start to be digested Long chains of sugar called Starch

  8. Digestive Enzyme Enzymes are biological catalysts A digestive enzyme is a protein that acts as a catalyst in breaking down food Amylase (saliva) Starch Sugar

  9. Saliva contains an ENZYME called Amylase- (speeds up the reaction) Digestion Amylase Maltase Glucose Shorter sugars that start to be digested Maltose Long chains of sugar called Starch

  10. Digestion –This also works with other groups for example proteins ENZYME Teeth begin process of breaking down food Eggs Amino Acids etc Used for growth and repair Complicated Protein

  11. To investigate the action of the digestive enzyme (amylase) on starch Add starch and saliva to two test tubes raise temperature to 37 degrees in a water bath Test one for starch (iodine) Test the other for glucose (Benedict’s solution and heat)

  12. Benedict’s solution Add Iodine solution To investigate the action of the digestive enzyme (amylase) on starch Heat it up Proves starch has turned to sugar Starch+Saliva Solution

  13. Substrate The substrate is the substance that an enzyme acts on. Starch is the substrate for the enzyme amylase. Notes on next page

  14. Summary Substrate Enzyme Product Starch Amylase Maltose

  15. Experiment To investigate the action of amylase on starch

  16. Aim • To see if we mix saliva and starch if the starch will turn into sugar

  17. Starch solution+Amylase Starch solution Water bath at 37°C Method To investigate the action of amylase on starch TUBE B TUBE A • Set up the apparatus as shown in the diagram. • Leave the apparatus for 10 minutes (to allow the amylase to act on the starch). • Remove a few drops of each solution and mix with a few drops of iodine solution (to test for starch).

  18. ResultsTo investigate the action of amylase on starch Final colour Tube Contents Conclusion No starch present Starch and amylase Tube A Red / yellow Starch present Starch Blue / black Tube B

  19. ConclusionTo investigate the action of amylase on starch • In tube A the starch was broken down by the action of the enzyme amylase. • In tube B starch was not broken down as there was no enzyme. This shows that amylasebreaks down starch.

  20. 5 Stages of Nutrition • Ingestion-Eating • Digestion-Breaking up • Absorption-Into body at small intestine • Assimilation-Used by the cells • Egestion-Pushed out

  21. The Oesophagus – Food Pipe. • 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.

  22. The Stomach • Muscular bag that holds 2 litres of food. • Secretes Hydrochloric Acid. • Makes digestive juices. • Muscular walls churn the food making sure it’s all mixed. • After 2-3 hours churning it’s a runny liquid. -CHIME

  23. The Small Intestine • Actually 6 m long! • Plays important roles in digestion and absorption • Two important liquids are added here: Pancreatic juices Bile

  24. 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

  25. Pancreas • Produces digestive enzymes • E.g. amylase • Also makes INSULIN to control sugar in body

  26. Liver • After food has been absorbed into the blood, the food is taken to the liver. • It removes toxins • The food dissolved in plasma is then taken to other parts of the body.

  27. 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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