- An infectious disease is caused by microorganisms (pathogens) entering and attacking your body. Common pathogens are bacteria and viruses.
- Bacteria - are singled cells living organisms. It is made up of cytoplasm surrounded by a membrane and a cell wall.
- Virus - are smaller than bacteria, they have regular shapes made up of a protein coat surrounding simple genetic material. They only carry out reproduction by taking over another living cell.
- Bacteria and viruses cause disease because they reproduce rapidly. Bacteria splits into two and produce toxins. Virus take over the cell in your body damaging and destroying them.
- Disease symptoms - high temperature, headaches and rashes. They are caused by the damage and toxins produced by the pathogens.
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- The skin, the platelets, the mucus of the breathing system prevents pathogens entering your body.
- The second line of defence are the white blood cells of your immune system.
1. The white blood cells ingest pathogens destroying them.
2. White blood cells produce antibodies.
3. Some white blood cells produce antitoxins.
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- Many types of bacteria have developed antibiotic resistance as a result of natural selection.
- We must not over use antibiotics.
- If bacteria or virus's mutate, new strains of a disease can appear whcih spread rapidly to cause epidemics and pandemics.
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