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Defending against infection.

Pathogens are microorganisms such as bacteria and viruses that
cause disease. Bacteria release toxins, and viruses damage our cells.
White blood cells can ingest and destroy pathogens. They can produce
antibodies to destroy pathogens, and antitoxins to neutralise toxins.

In vaccination pathogens are introduced into the body…

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1.influenza ­ flu.

2.colds.

3.measles.

4.mumps.

5.rubella.

6.chicken pox.

7.AIDS.

White blood cells.
The body has different ways of protecting itself against pathogens. The
first defence is passive immunity. This is aimed at stopping the pathogen
getting into the body in the first place. The body's passive immunity
system includes…

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More about white blood cells
There are several different types of white blood cells, each with different
functions, but they can be put into two main groups:

1.phagocytes or macrophages.

2.lymphocytes.

Phagocytes
Phagocytes can easily pass through blood vessel walls into the
surrounding tissue and move towards pathogens or toxins.…

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Vaccination involves putting a small amount of an inactive form of a
pathogen, or dead pathogen, into the body. Vaccines can contain:

1.live pathogens treated to make them harmless.

2.harmless fragments of the pathogen.

3. toxins produced by pathogens.
4. dead pathogens.

These all act as antigens. When injected into…

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overuse of antibiotics, so we can slow down, or stop, the development
of other strains of resistant bacteria.
Cleanliness.One simple way to reduce the risk of infection is to maintain
personal hygiene and to keep hospitals clean. In the 19th century, Ignaz
Semmelweis realised the importance of cleanliness in hospitals.…

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