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1.1- Pathogens
- Microorganism is a general term for a single-celled organism that is too
small to be seen without a microscope
- Includes Bacteria and Viruses
- Some are beneficial to us, some cause harm
- Includes Bacteria and Viruses
- A Pathogen is a Microorganism that causes disease
- Include: Fungi, Viruses and Bacterium
- Include: Fungi, Viruses and Bacterium
- A disease is a description of symptoms which suggests a
malfunction of body or mind, and has social, mental and physical
aspects.
- For a Microorganism to be considered as a Pathogen
- Gain entry to the host
- Colonise the tissue of the host
- Resist the defences of the host
- Cause damage to host tissues
- Gain entry to the host
- If a Pathogen gets into the host and colonises its tissue an infection
results
- Disease occurs when an infection leads to recognisable symptoms
in the host
- When a Pathogen is transferred from one individual to another it is
known as transmission
- How do they enter the body?
- The gas-exchange system, e.g.
influenza, tuberculosis and bronchitis
- The digestive system, (through food and water) e.g.
cholera, typhoid, and dysentery pathogens
- The gas-exchange system, e.g.
influenza, tuberculosis and bronchitis
- How do they cause disease?
- By damaging host tissues- breaking down
the cell membrane or a virus inhibits the
synthesis of DNA, RNA and proteins
- By producing toxins- (most bacterial) e.g. cholera bacterium
produces a toxin that leads to excesssive water loss from the
lining of the intestines
- By damaging host tissues- breaking down
the cell membrane or a virus inhibits the
synthesis of DNA, RNA and proteins
- Prevention of entry
- The production of stomach
acid, which kills microorganisms
- Mucous layer that covers exchange surfaces, thick
and sticky, hard to penetrate
- The production of
enzymes that break
down pathogens
- The production of stomach
acid, which kills microorganisms
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