Starter (from the end of last lesson) 1.What are the similarities between a virus and bacteria?

1. 1. How are diseases spread? Title: Defence Mechanisms Starter (from the end of last lesson) • 1.What are the similarities between a virus and bacteria? • 2. What are the main differences between a virus and bacteria? • 3. Draw a flow diagram to explain how viruses replicate. • 4. Name three viral diseases. • 5. Why are viral diseases much harder to treat than bacterial diseases? 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

2. 1. How are diseases spread? Defence Mechanisms Ways of Spreading Diseases There are four main ways that pathogens are spread from one person to another. 2. How does your body stop pathogens getting in? • Droplet Infection • Direct Contact • Contaminated Food and Drink • Through a break in the skin 3. How do white blood cells protect us from disease?

3. 1. How are diseases spread? Defence Mechanisms Droplet Infection • When you cough, sneeze or talk, tiny droplets full of pathogens are expelled into the air. Other people breathe these in. • E.g. Tuberculosis, Influenze, Common Cold 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

4. 1. How are diseases spread? Defence Mechanisms Direct Contact • Some diseases spread by direct contact of the skin. • e.g. Impetigo, Genital Herpes 2.How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

5. 1. How are diseases spread? Defence Mechanisms Contaminated Food and Drink • Eating raw or undercooked food, or drinking water containing sewage can spread disease. • E.g. Salmonella, Cholera 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

6. 1. How are diseases spread? Defence Mechanisms Through a Break in the Skin Pathogens can enter the body through cuts, scratches and needle punctures E.g. HIV, Hepatitis 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

7. 1. How are diseases spread? Defence Mechanisms Task 1 • Describe the four main ways in which infectious diseases are spread. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

8. 1. How are diseases spread? Defence Mechanisms Preventing Microbes Getting In • There are three main barriers to infection. 2.How does your body stop pathogens getting in? • The Skin • Scabbing • Mucus and Stomach Acid 3. How do white blood cells protect us from disease?

9. 1. How are diseases spread? Defence Mechanisms Preventing Microbes Getting In • The skin prevents bacteria and viruses from getting to your tissues underneath. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

10. 1. How are diseases spread? Defence Mechanisms Preventing Microbes Getting In • If you cut your skin, you bleed. Your blood quickly clots and forms a scab. This prevents any pathogens from entering. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

11. 1. How are diseases spread? Defence Mechanisms Preventing Microbes Getting In • When you breathe, you draw in air full of pathogens. Your breathing system produces mucus which traps them. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

12. 1. How are diseases spread? Defence Mechanisms Preventing Microbes Getting In • The mucus can then be removed from the body (blowing your nose) or swallowed into the gut, where stomach aciddestroys the pathogens. 2.How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

13. 1. How are diseases spread? Defence Mechanisms Task 2 • Copy and complete the following table 2.How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

14. 1. How are diseases spread? Defence Mechanisms How White Blood Cells Protect Against Disease • Some pathogens still get through the barriers to infection. The body however has a second line of defence - the white blood cells of the immune system. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

15. 1. How are diseases spread? Defence Mechanisms How White Blood Cells Protect Against Disease • White blood cells protect fight pathogens in three main ways. 2. How does your body stop pathogens getting in? • Ingesting Microorganisms • Producing Antibodies • Producing Antitoxins 3. How do white blood cells protect us from disease?

16. 1. How are diseases spread? Defence Mechanisms Ingesting Microorganisms • Some white blood cells ingest (take in) pathogens, destroying them so they can’t make you ill. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

17. 1. How are diseases spread? Defence Mechanisms Producing Antibodies • Some white blood cells produce antibodies that bind to antigens on bacteria and viruses and destroy them. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

18. 1. How are diseases spread? Defence Mechanisms Producing Antibodies • Once your white blood cells have made an antibody for a specific pathogen, if you get re-infected, these antibodies can be made very quickly. This is immunity. 2. How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?

19. 1. How are diseases spread? Defence Mechanisms Task 3 • Explain how white blood cells work using combination of sentences and labelled diagrams. • Key words: Antibodies, antigens, antitoxins, 2.How does your body stop pathogens getting in? 3. How do white blood cells protect us from disease?