Starter

1. Should you take Antibiotic for every illness? Why?No, Viruses cannot be killed by antibiotics

2. Why do people take painkillers when they have an infection?To relieve the symptoms and allow the body to fight the infection while we carry on with our lives

Immunity and immunisation

Key Words: Immune system, antibody, antigen, immunity,

immunisation, epidemic, pandemic

By the end of the lesson I will be able to answer

• How do our bodies stop pathogens entering?

• What happens to us when pathogens do get into our bodies?

• How do our bodies respond?

How do our bodies stop pathogens entering?

• Skin

• Tears

• Stomach acid

• Mucus in the airways

• Blood clotting when you cut yourself

White blood cells

• Immune system = white blood cell Two main types of white blood cell

Phagocytes engulf (ingest) the pathogen (germ)

Lymphocytes produce antibodies or antitoxins

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/human/defendingagainstinfectionrev4.shtml

Check point

Sometimes some pathogen manage to enter your body. When they do your immune system may deal with them. This involves your white blood cells.

You have different sorts of white blood cells • Phagocytes engulf(ingest) the pathogens• Lymphocytes produces antibodies or antitoxins

Antibodies

• Each Type of antibody can destroy a particular types of bacterium or virus

– Each type of pathogen has particular antigens (proteins) – with a specific shape on the surface

– Each antibody ( protein) has a particular shape which locks (Fits) in to the antigen

– When it is coated the Phagocytes can ingest them

Animation

Immunisation

• A small amout of dead or inactive pathogen is introduced to your body

• White blood cells recognise the pathogen and respond to them by making antibodies

• If the living pathogen gets into your body the white blood cells quickly make the right antibodies

• Which destroys the pathogen

Checkpoint

• Antibodies are proteins. • Each type of the pathogen has particular antigens

(proteins) with a specific shape on its surface.• Each type of antibody (also proteins) has a particular

shape and can lock onto a particular antigen. • Once the pathogen is coated with antibodies, white

blood cells can ingest and kill the pathogen• Once you have recovered from this infection, you have

immunity to it. If the same pathogen enters your body again your body will be able to react quickly

Finally

• Describe one way a pathogen can enter your body

• What is a antigen?

• What is an antibody?