The Digestive System Chapter 4 Nutrition takes place

The Digestive System Chapter 4

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)

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.

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

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.

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

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