1. © Oxford University Press 2009 These microbes got in through Will’s cut finger. Left unchecked they will reproduce rapidly and fill his blood and tissues with toxins. We will discover how Will’s immune system can stop them. 2.2 Destroying invaders Slide 1

2. © Oxford University Press 2009 It looks yellow on the image, but this is a white blood cell. What is it doing? ‘Engulfing the bacteria?!!’ 2.2 Destroying invaders Slide 2

3. © Oxford University Press 2009 Once the bacteria are inside, enzymes destroy them. The white cells eventually die and get broken down. The broken down cells ooze out of wounds as pus. 2.2 Destroying invaders Slide 3

4. © Oxford University Press 2009 Other types of white blood cells defend the body in different ways. They make chemicals called antibodies which stick to microbes and make them easier to destroy. They work against both bacteria and viruses. 2.2 Destroying invaders Slide 4

5. © Oxford University Press 2009 These Y-shaped particles are models of antibodies. Each type of microbe needs a different antibody, so they aren’t made in advance. When a new microbe invades the body, it takes a couple of days to make them. 2.2 Destroying invaders Slide 5

6. © Oxford University Press 2009 Once a white blood cell has made antibodies, it never forgets its target. If that microbe returns, it makes antibodies straight away. So the microbes are destroyed before they can reproduce and cause disease…...which makes you immune to that disease. 2.2 Destroying invaders Slide 6

7. © Oxford University Press 2009 Paul is beginning to feel ill. Bacteria have infected his throat. He is under a lot of stress and it has weakened his immunity. 2.2 Destroying invaders Slide 7

8. © Oxford University Press 2009 Explain what is happening in each part of the graph. 2.2 Destroying invaders Slide 8

9. © Oxford University Press 2009 2.2 Destroying invaders What would help Paul get better quicker? Slide 9 ( Think about what most people do when they are ill. )

10. © Oxford University Press 2009 2.2 Destroying invaders Why doesn’t Paul notice the second infection? Slide 10

11. © Oxford University Press 2009 Asha has AIDs. She gets a lot of infections and feels tired all the time. This white cell used to help Asha make antibodies…..but HIV particles have stopped it working…..so her immune system cannot protect her. 2.2 Destroying invaders Slide 11

12. © Oxford University Press 2009 Slide 12

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15. © Oxford University Press 2009 Slide 15

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18. © Oxford University Press 2009 The broken down cells ooze out of wounds as pus. Slide 18

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23. © Oxford University Press 2009 You are a microbe. You want to get into Will’s body. Are you lucky or unlucky? 2.2 Lucky or unlucky? Slide 23

24. © Oxford University Press 2009 You’re with a group of salmonella bacteria in the middle of a burger. What happens next? 2.2 Lucky or unlucky? Slide 24

25. © Oxford University Press 2009 You’re are a cold virus. You drifted into Will’s nose as he breathed. What happens next? 2.2 Lucky or unlucky? Slide 25

26. © Oxford University Press 2009 You are a tetanus bacterium in the mud on Will’s football. He has a cut on his finger and he has just picked up the football. What happens next? 2.2 Lucky or unlucky? Slide 26

27. © Oxford University Press 2009 Slide 27

28. © Oxford University Press 2009 Slide 28