1. The Digestive System
Chapter 4

2. Nutrition Nutrition takes place in 5 stages
Ingestion-Taking in of food
Digestion-breakdown of food
Absorption- into bloodstream through the small intestine
Assimilation- Absorbed food enters the cells
Egestion-removal of undigested food (fibre)

3. The main parts of the Digestive system
Mouth – Where food is chewed and mixed with saliva(enzyme amylase)
Oesophagus- carries food from mouth to stomach by peristalsis.
Stomach- produces digestive juices.
Liver- produces bile which helps in the digestion of fats.
Pancreas-produces digestive enzymes.
Small Intestine- absorption of food into bloodstream.
Large Intestine- Water taken back into bloodstream and waste stored.

4. The Teeth There are 4 tooth types Incisors- Cutting and Biting Food
Canine – Tearing of food
Pre-molar – grinding of food
Molars – grinding of food

5. Chemical Digestion
Chemical digestion involves the use of chemicals, called enzymes, to chemically break down food.
They are biological catalysts (speeds up a chemical reaction).
An enzyme acts on its substrate and breaks it down into its products.
Starch is broken down by the enzymes amylase and maltase to form glucose.

8. Experiment:To show the action of Amylase on Starch.
a) Set up test tubes as shown in diagram. b) Place the test tubes in a water bath at 370 for 5 minutes

9. c) Remove the tubes from the water
c) Remove the tubes from the water. d) To A and B add a few drops of Iodine solution e) To C and D add Benidicts solution.
Result:
Tube A black blue colour is formed
Tube B no change
Tube C No change
Tube D Brick red colour is formed