Micro organisms & Disease

Micro organisms & Disease

1. Not all micro organisms are harmful to the body; these are called a pathogen which are a microbe causing the body to react against the disease

   • Vaccination: Weakened, Inactive, Protein Coat > Lymphocytes > Antibodies in response to an antigen > Pathogen destroyed > Memory Cells > Makes antibodies if re-encountered

2. Bacteria: Living, usually only one cell large (e.g ecoli, salmonella, food poisoning, cholera, typhoid, MRSA)

3. Fungi: Live on dead/living matter (e.g athletes foot)

4. Viruses: NOT living things, need a host (e.g flu, cold, rubella, chicken pox, HIV)

5. Microbes can spread by: Coughing/sneezing (e.g cold). Directly inserted (e.g needles). Contaminated food (e.g salmonella). Contact (e.g conjunctivitis). Animal hosts (e.g plague:rats & malaria:mosquitoes). Wounds & Sexual contact (e.g aids)

6. Microbes stopped by: Vaccination. Antibacterial agents. Body defences (e.g antibodies). Skin. Antibiotics. Cilia/mucus. Saliva. Stomach acid. Earwax. Contraception.

7. White Blood Cells

   • Engulf the microbe > digest
   • Antibodies: very specific, takes several days to produce

8. Every microbe has its own unique antigen pattern on the surface. From this the WBC can produce antibodies that match the antigen exactly. This is called the lock and key theory. The antibodies made will fight the microbe and the antibodies will remain in the body in the form of memory cells. If the same antigen pattern is exposed again, the microbe is quickly destroyed- we say the person is immune.

9. Vaccines can contain one of the following: A weakened strain of the virus. Dead virus (deactivated). Antigen coat.

10. When a person is vaccinated, the body will respond in a similar way as if the pathogen was naturally encountered. Memory cells would be produced and if the pathogen was to be encountered again, a rapid response would occur.

11. White Blood Cells

    • Lymphocytes - can produce specific antibodies to kill a particular pathogen
    • Phagocytes - they coat pathogens, clumping them together so that they are easily ingested by white blood cells

12. Example of microbes not simply appearing: Louis Passteur's investigation with a swan necked flask and broth at the other end. Bacteria gathered but because the curve in the flask, it wasn't able to reach the broth.