Today we are learning:
• How our understanding of the spread and prevention of disease has developed
• About the natural barriers we have to fight infection
• That we make antibodies and specialised cells in the blood to fight microbes
Keywords:
Hygiene, immunity, vaccination, antibodies.
Starter:
Label the microbes
Extension:
What happens to your body when you catch a cold? Discuss in pairs.

Virus
A virus is a simple organism which does not completely display ALL the characteristics of living things. It consists of a protein coating and a strand of genes.
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Bacteria
A bacteria is a single celled organism which does not completely have a nucleus. Their genes are found in the chromosomes.
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Fungus
Yeast is a fungus and as can be seen below, it has a more complex structure than the other two types of microbes.
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By the end of the lesson you should be able to describe:
• how micro-organisms can cause infections and can be passed from one person to another.
• how bias, lack of evidence or misconceptions can give rise to inappropriate theories and the role of scientists in questioning these’.

John Snow ( 1813 1858 ) was a
British physician.
He is considered to be one of the fathers of epidemiology , because of his work in tracing the source of a cholera outbreak in Soho , England , in
1854.


We know cholera is caused by a bacterium
(Vibrio cholerae).

Symptoms include chronic diarrhoea, low blood pressure and dehydration.

Infected patients can die within 3 hours if left untreated.

In 1854, there was a cholera outbreak in Soho, London.
It had devastating outcomes with over 500 fatalities.
Nearly all families lost at least one member (regardless of socioeconomic class).

People thought that cholera was caused by ‘bad’ air
John Snow did not believe this and he began to collect evidence

• Complete the worksheet including report
(15 minutes total)

By talking to local residents, Snow identified the source of the outbreak as the public water pump on Broad Street.

Snow later used a spot map to illustrate how cases of cholera were centred around the pump.

Snow concluded that all the people infected with cholera had drunk water collected from the Broad
Street well.
It was later discovered that a leaking cess pit containing sewage was only 3ft away from the well and was contaminating the water.

Snow's studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle.
This caused the number of cholera cases to decrease rapidly.

Many years ago there was a disease called SMALLPOX, people living in the countryside noticed that milkmaids never seemed to catch the deadly disease.
This was because they were subjected to another similar infection caught from the cows they milked (cowpox).

In 1796 a doctor called
Edward Jenner carried out a famous experiment on an eight year old boy called
James Phipps.

Jenner took pus from someone with mild cowpox and put it into a cut in the eight year olds arm.
He never caught smallpox, for many years after that
Jenner conducted lots of experiments to prove that our bodies can become
IMMUNE.

• Do you think the experiment that Dr. Jenner did on James was a dangerous one?
• If you were James' parents, would you let Dr.
Jenner do the experiment on James? What questions would you ask Dr. Jenner?
• If you were James, now that you are safe from contracting smallpox, would you advise your friends to have the vaccination?

Fighting disease
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Fighting disease
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• Explain how white blood cells defend against disease (can use diagrams ) 5 minutes
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Our bodies have many defence mechanisms against invading microbes:
The skin acts as a barrier
Tears contain an enzyme that kills bacteria
Stomach produces stomach acid
If our skin is cut platelets seal the wound by clotting
The breathing organs produce mucus to cover the lining of these organs and trap the microbes

Ear wax traps them
On your outline of the human body, label how we stop microorganisms getting into our bodies.
Here is an example for you.

Turn to the back of your book and put 1 to 10 in the margin.
The questions will pop up, answer them as quickly as possible.

3.
4.
2.
1. Name the 3 main types of microbes
Which organ uses acid to kill microbes?
What do white blood cells make to fight microbes?
Name the doctor that experimented with smallpox
5.
What does engulf mean?
5 correct LEVEL 5+
4 correct LEVEL 4
2-3 correct LEVEL 3
0-1 correct LEVEL 2

We are going to look at how we can kill bacterial.
We need to grow some bacteria to look at next lesson.
Listen carefully to your instructions and make sure you wear goggles!