1. Diseases caused by Bacteria, Fungi and Viruses

2. Introduction  The body is constantly surrounded by microbes  It has many defence mechanisms to prevent against pathogens  The first defence is to stop pathogens getting into the body.

3. Preventing microbes getting into the body  Skin is bacteria proof: Thick outer layer that secretes oils and salt which kills many pathogens  Saliva, stomach acid and tears also contain chemicals to kill pathogens  Immune system: kills many pathogens that gain entry to the body

4. The Immune System  Symptoms of diseases develop when the pathogen reproduces rapidly before it can be destroyed.  Diseases can be caused by microbes.  Some are parasites and cause damage by sapping energy and weakening the living organsism

5. Pesticides  Chemicals made to kill unwanted organisms. Herbicides kill unwanted plants, Insecticides kill unwanted insects and Fungicides kill fungi.

6. Vaccines  Offer protection against some bacterial diseases  Can help the immune system produce antibodies to fight off particular diseases  Some supply ready made antibodies, most useful for diseases that kill too quickly for the body to make its own. However in this case immunity only lasts for a certain time like tetanus, therefore you have to get booster shots.

7. Vaccines  Viral diseases are hard to manage due to mutation of the virus. By the time a treatment is discovered the virus has mutated so it is less effective at killing it.

8. Antibiotics  Taken internally as pills or solutions, they destroy pathogenic bacteria but don’t harm living tissue.  Penicillin is the first antibiotic, but since then many more have been produced.  Bacterial infections were the main cause of human deaths until the development of antibiotics.

9. Antibiotics  Produced by a living organism which inhibits the growth of other kinds of organisms.  Some kill bacteria, others slow bacterial growth giving the body’s immune system a fighting chance.  Useless against viruses as they have no chemical processes (metabolism)

10. Disinfectants  Powerful microbe killers.  Used to clean toilets, floors etc  E.g. Janola, “PINE O CLEAN”

11. Antiseptics  Used in cleaning living tissue, such as scratches and wounds  E.g. Savlon, Dettol

12. Resistance to Antibiotics  Some strains of bacterial diseases have developed resistance to antibiotics. This means larger and larger doses of antibiotic are needed to kill pathogens.

13. Red is resistant pathogens Yellow not resistant  1st step: The original pathogens  2nd step: antibiotic taken  3rd step: reproduction of resistant bacteria

14. Resistance to Antibiotics  If this process happens repeatedly, the resulting bacteria can be totally unaffected by the antibiotic.  These are commonly called super-bugs  Some countries estimate that up to 30% of bacteria show signs of resistance to drugs normally prescribed for their treatment.

15. Resistance to Antibiotics  Hence why when you are given a prescription you are told to take all the antibiotics even if you get better.  Scientists think that this drug resistance is the result of over prescribing. I.e. prescribing a drug that is more potent antibiotic than needed.  Also when people don’t take the full prescription some bacteria may still be present and survive.

16. How Bacteria Cause Diseases  Bacteria harm the body by killing the cells they attack. (TB live inside defence cells of the body and attack other healthy cells)  Some of the most deadly bacteria cause disease by producing poisonous substances (TOXINS) as waste products from excretion.

17. Bacterial disease examples  Botulinus: prevents transfer of signals from nerve to muscle including breathing muscles. 1g can kill 15 mill humans.  Tetanus: prevents muscles relaxing, after entry into wounds  Cholera: causes diarrhoea, can lead to death due to dehydration

18. How is Disease Spread  Direct Contact  Droplets (colds + flu)  Drinking water  Food  Insects  Infected needles and surgical instruments

19. Summary Notes  The body prevents pathogens entering the body by: skin, saliva, stomach acid, tears and the immune system.  Treating Diseases:  Pesticides:  Vaccines:  Antibiotics:  Disinfectants:  Antiseptics:

20. Use your understanding science book and ESA to fill in the following  How resistance to Antibiotics is developed:  How bacteria cause disease:  How disease is spread: