Microorganism And Disease


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Microorganism And Disease

  1. 1. Unit 3: It's a Small World Microorganisms and Disease
  2. 2. What Do You Think? When you “catch a cold,” what is it that infects your body?
  3. 3. Germ Theory  Idea that microorganisms can and are the cause of many diseases  Originally proposed back in 1020 A.D. and built upon by many different scientists  Microorganisms were first observed by Anton van Leeuwenhoek  Louis Pasteur, a French chemist, helped to disprove another competing theory and his
  4. 4. Germ Theory  Joseph Lister, an English surgeon, was one of the 1st to realize the importance of germ theory  He used chemicals on wounds to kill germs  Also made sure that everything that touched his patients was washed in a chemical solution so that it was free of germs
  5. 5. Antiseptics = Disinfectants?  Antiseptics are for use on people  Disinfectants are for use on objects and surfaces.
  6. 6. Robert Koch  1st to actually demonstrate that microorganisms do cause disease  Studied anthrax  While investigating the disease, he developed a set of rules for proving that a microorganism is the cause of a specific disease.  These rules are called Koch’s postulates and they are a good example of the scientific method.
  7. 7. Koch’s postulates 1. The microorganism must be found in abundance in all organisms suffering from the disease, but not in healthy organisms. 2. The microorganism must be isolated from a diseased organism and grown in pure culture.
  8. 8. Koch’s postulates 3. The cultured microorganism should cause disease when introduced into a healthy organism. 4. The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original agent.
  9. 9.  List as many different diseases as you can.
  10. 10. Diseases  2 types of disease  Noninfectious diseases: diseases that are not spread from one person to another  Infectious diseases: diseases that can be passed from one living thing to another
  11. 11. What causes disease?  Noninfectious diseases can be caused by many different factors. Smoking, lack of physical activity, and a high-fat diet can greatly increase a person’s chances of getting many noninfectious diseases.  Infectious diseases are caused by pathogens
  12. 12. Think, Pair, Share  How is an infectious disease different from a noninfectious disease?
  13. 13. Did You Know?  Before the mid-1800’s, doctors and surgeons rarely washed their hands before surgery.  This was because pathogens were not known about  Many people believed that if someone got a disease it was because they were being punished
  14. 14. Pathways to Pathogens  Look at p.S68 in your textbook. What are two ways that infectious diseases are spread?
  15. 15. Pathways to Pathogens  There are many ways pathogens can be passed from one person to another. Being aware of them can help you stay healthy. 1. Through the air: a single sneeze releases thousands of tiny droplets of moisture that can carry pathogens
  16. 16. Pathways to Pathogens 2. Contaminated objects: person who is sick may leave bacteria or viruses on objects such as doorknobs, keyboards, drinking glasses, towels, or combs. 3. Person to Person: may become infected with some illnesses by kissing, shaking hands, or touching the sores of an infected person
  17. 17. Pathways to Pathogens 4. Animals: some pathogens are carried by animals; humans can get ringworm from handling an infected dog or cat. Also, ticks can carry bacteria that cause Lyme disease. 5. Food and water: water lines can break or treatment plants can become flooded allowing microorganisms to enter the public
  18. 18. Brain Food  In developing countries, 80% of diseases are related to contaminated drinking water.
  19. 19. Inferring Relationships  Why might the risk of infectious disease be high in a community that has no water treatment facility?
  20. 20. Checkpoint  Jackie cut up raw meat on her kitchen counter. If her brother makes a sandwich on the same counter later, how could he come in contact with a pathogen?
  21. 21. Causes of Infectious Disease  Bacteria are one kind of microorganism that can cause an infectious disease. Can affect the human body in different ways  Bacteria can kill cells and tissues  Other bacteria do damage by releasing toxins
  22. 22. Causes of Infectious Disease Viruses  Smallest of disease-causing microorganisms  Even the largest virus can just barely be seen with a light microscope  Common cold, influenza, warts, rabies, AIDS, Ebola
  23. 23. Causes of Infectious Disease Protozoans  Malaria and sleeping sickness Fungi  Cells of the fungus enter the body through the digestive or respiratory system  Athlete’s foot and ringworm
  24. 24. Think, Pair, Share  What are the four causes of infectious disease?  Which cause involves toxins?  Which cause is at fault when you have the flu?