Transcript 2.2 Destroying invaders

2.2 Destroying invaders
These microbes got in through Will’s
cut finger.
Left unchecked they will reproduce
rapidly and fill his blood and tissues
with toxins.
We will discover how Will’s
immune system can stop them.
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2009
2.2 Destroying invaders
It looks yellow on the image, but
this is a white blood cell.
What is it doing?
‘Engulfing the bacteria?!!’
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2.2 Destroying invaders
Once the bacteria are inside,
enzymes destroy them.
The white cells eventually die
and get broken down.
The broken down cells ooze out
of wounds as pus.
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2009
2.2 Destroying invaders
Other types of white blood cells defend the body in
different ways.
They make chemicals called antibodies which stick to
microbes and make them easier to destroy.
They work against both bacteria and viruses.
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2.2 Destroying invaders
These Y-shaped particles are models
of antibodies.
Each type of microbe needs a
different antibody, so they aren’t
made in advance. When a new
microbe invades the body, it takes a
couple of days to make them.
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2.2 Destroying invaders
Once a white blood cell has made
antibodies, it never forgets its target.
If that microbe returns, it makes
antibodies straight away. So the
microbes are destroyed before they can
reproduce and cause disease…
...which makes you immune to that
disease.
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2.2 Destroying invaders
Paul is beginning to feel ill.
Bacteria have infected his
throat.
He is under a lot of stress
and it has weakened his
immunity.
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2.2 Destroying invaders
Explain what is happening in each part
of the graph.
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What would help Paul get better quicker?
( Think about what most people do when they are ill. )
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Why doesn’t Paul notice the second infection?
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Asha has AIDs.
She gets a lot of infections and feels tired all the time.
This white cell used to help Asha make antibodies…
..but HIV particles have stopped
it working…
..so her immune system
cannot protect her.
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The broken down cells ooze out of wounds as pus.
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2.2 Lucky or unlucky?
You are a microbe.
You want to get
into Will’s body.
Are you lucky
or unlucky?
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2.2 Lucky or unlucky?
You’re with a group of salmonella bacteria in
the middle of a burger.
What happens next?
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2.2 Lucky or unlucky?
You’re are a cold virus.
You drifted into Will’s nose as he breathed.
What happens next?
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2.2 Lucky or unlucky?
You are a tetanus bacterium in the
mud on Will’s football. He has a cut
on his finger and he has just picked
up the football.
What happens next?
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