Biology Core 1.1 Healthy Living

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  • Created by: Shaye :)
  • Created on: 24-11-13 22:06

Biology 1.1 Healthy Living

 

Microbes and disease

  • Microbes need four things to reproduce:

    • Time

    • Warmth

    • Food (oxygen)

    • Moisture

  • This makes our bodies perfect hosts for bacteria to grow, which means once inside our body, they can multiply rapidly and make us ill

  • Pathogens are microorganisms which can cause infectious disease, and are surrounded by unique molecules called antigens

  • Bacteria- are very small cells which can rapidly reproduce by cell division in your body making you feel ill by damaging your body's cells and producing toxins

  • Viruses- are NOT cells and much smaller than bacteria and damage the cells in which they reproduce. Viruses replicate by invading a cell and using the cell's genetic machinery to reproduce themselves ie copies of the original virus.The virus 'invaded' cell then bursts releasing lots of new viruses.

  • We have many defences which stop pathogens from entering our body and protecting us once they are inside:

    • Skin

    • Tears

    • Nose hairs

    • Mucus in the throat

    • White blood cells

  • Antibodies fight the virus whereas antitoxins counteract the toxins released by bacteria which make us feel ill by attacking and damaging our cells

  • If a recognised pathogen enters our body, our white blood cells attack it:

    • Phagocytes- Ingest /engulf pathogens

    • Lymphocytes- produces antibodies to destroy the antigen and produces antitoxins that neutralise released toxins

  • Having absorbed a pathogen, phagocytes may also send out a chemical message to nearby lymphocytes to identify the type of antibody needed to neutralise them

  • After a pathogen has been destroyed by our white blood cells, some cells still remain and ‘remember’ the pathogen, so if it enters again our antibodies will attack the pathogen

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