1. Fighting infections viral infection – video link
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2. White Blood Cells!!

3. The scientific name for white blood cells is leukocytes
They have a short life cycle, living from a few days to a few weeks. A drop of blood can contain anywhere from 7,000 to 25,000 white blood cells at a time.

4. white blood cells are continually on the lookout for signs of disease.
When a germ does appear, the white blood cells have a variety of ways by which they can attack.
The number of WBCs in the blood is often an indicator of disease.

5. White blood cells are capable of passing through the walls of capillaries (tiny blood vessels) in order to attack, kill and consume intruder germs.

6. TYPES OF WHITE BLOOD CELLS
One type of white blood cell is called a B cell. These cells are responsible for making antibodies.
Antibodies are made to connect with things called antigens that are found on the surfaces of bacteria

7. 1. They make the appropriate antibody to fit ‘lock and key’
B cells will travel around in your blood looking for bacteria with antigens on them
1. They make the appropriate antibody to fit
‘lock and key’
2. Once the antibodies are connected to the antigens, it allows the bacteria to be recognised by engulfing white blood cells
(making antibodies) – optional video link
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8. B cells are really cool because they remember how to make the antibodies they create.
In this way, if you are infected by the same microbe again, your body already knows how to fight it!

9. (Immunity)- optional video link
The faster your body responds to an invading microbe, the less ill you get and the faster you recover.
Your immune system works because it remembers all past infections and how to fight them
(Immunity)- optional video link
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10. TYPES OF WHITE BLOOD CELLS
A second type of white blood cell ‘eats’ or engulfs bacteria. They are called phagocytes
Phagocytes are able to tell what’s foreign because of the antibody/antigen interaction
Antibody response – video link

11. TYPES OF WHITE BLOOD CELLS
A third type of white blood cell makes chemicals called antitoxins.
Remember: many bacteria and viruses release toxins into your blood that cause illness
Antitoxins are chemicals your body makes to counteract the harmful toxins

12. Note: White blood cells are also called Leukocytes
Three ways to fight an infection:
Produce antibodies to antigens found on the surface of bacteria
To engulf or eat the infecting microbes
To produce anti-toxins to toxins produce by invading bacteria