Infectious diseasesWALT: To understand how vaccination can be used to prevent some diseases.

WILF: State what a pathogen is and name examples. (PASS)Describe how bacteria and viruses can cause infectious disease. (MERIT)Explain how vaccinations can be used to prevent infection. (DISTINCTION)

KeywordsPathogenBacteriaVirusVaccine Memory cells

What is a pathogen? A microorganism that causes an infectious disease. They can be:

~ a bacteria

~ a virus

E.Coli

Influenza

Bacteria

Diseases Caused: CholeraFood poisoningTuberculosis (TB)Dysentery

DNA

DNA Flagellum

Cell membrane

Cell wall

How? Enter the body and produce toxins that harm our cells.

Virus

Diseases Caused: InfluenzaAIDSMeaslesMumps

Genetic materialProtei

n coat

How? Viruses cannot reproduce by themselves, they need a host. They invade our cells and make copies of themselves.

Food may contain food poisoning bacteria like salmonella.

Water may contain bacteria that may cause cholera.

Influenza and cold viruses can be spread through the air through coughs and sneezes.

The HIV can be transferred through body fluids via sexual intercourse or sharing of syringes.

Houseflies can pass the dysentery bacteria from human faeces to food.

So a pathogen has managed to beat all our defences, what happens next?

Our immune system is ready to fight!

Our immune system ismade up of differenttypes of white bloodcells.

White blood cells that are ready and waiting.

They can pull (engulf) pathogens inside them and digest them.

At the site of the infection…

Bacteria

White blood cell

In your blood…If the microbes don’t all get killed, your next line of defence is launched – antibodies. Antibodies are produced by special white blood cells called B cells.

These zoom round in your blood like guided missiles until they lock onto their target (pathogen), making it easier to be destroyed.

Once you’ve defeated an infection, antibodies stay in your blood but…

… antibodies only last a few days,but memory cells, which remember how to make them, last a lifetime.

These make antibodies so quickly that the microbes are all destroyed before they can make you ill.

People can become immune against a pathogen through vaccination.  

Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body. When injected into the body, they stimulate B cells to produce antibodies against the pathogen and produces memory cells.  Different vaccines are needed for different pathogens.

Task: Create a storyboard or flow chart showing how vaccines work.

Patient is injected with an inactive pathogen, this is the vaccine.

White blood cells produce antibodies, which attach to the pathogen.

Following the antibodies being made, memory cells are then made.

Memory cells remain in the blood in case you later become infected.

The patient is now immune.

Vaccinations-worth it? e.g. MMR vaccineMeaslesMumpsRubella

e.g. HPV vaccine

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How a pathogen can enter the body?

Example? Bacteria or virus?

Salmonella

Contaminated water.

Transferred through body fluids, for example…

Influenza (flu)

Houseflies landing on faeces and then onto food. How a pathogen can enter the body?

Example? Bacteria or virus?

Salmonella

Contaminated water.

Transferred through body fluids, for example…

Influenza (flu)

Houseflies landing on faeces and then onto food.

How a pathogen can enter the body?

Example? Bacteria or virus?

Salmonella

Contaminated water.

Transferred through body fluids, for example…

Influenza (flu)

Houseflies landing on faeces and then onto food.

How a pathogen can enter the body?

Example? Bacteria or virus?

Salmonella

Contaminated water.

Transferred through body fluids, for example…

Influenza (flu)

Houseflies landing on faeces and then onto food.