AQA Science © Nelson Thornes Ltd 2006  1

B1a 4.6 Immunity

Immunity

Lesson objectivesTo describe how the immune system works.

To evaluate how vaccination can help prevent some bacterial and viral diseases.

B1a 4.6 Immunity

WHAT VACCINATIONS HAVE YOU HAD?

AQA Science © Nelson Thornes Ltd 2006  2

B1a 4.6 Immunity

What vaccinations have you had?

• Diphtheria • Tetanus• Whooping cough (pertussis) • Polio• Hib: vaccination against the bacteria Haemophilus influenzae type B,

which can cause meningitis, • Measles • Mumps • Rubella (German measles) • Meningitis C • Pneumococcal: vaccination against the bacteria Streptococcus

pneumoniae (known as pneumococcus), which can cause meningitis.

AQA Science © Nelson Thornes Ltd 2006  3

B1a 4.6 Immunity

Immune system

• Every cell has unique proteins on its surface called antigens.

• As we have covered your white blood cells recognise antigens on pathogens as different.

• Your white blood cells make antibodies to attack and kill the pathogens.

AQA Science © Nelson Thornes Ltd 2006  4

AQA Science © Nelson Thornes Ltd 2006  5

B1a 4.6 Immunity

The diseases that children are commonly vaccinated against were once childhood killers.

B1a 4.6 Immunity

Immune system

• White blood cells are able to remember the right antibody needed to tackle a particular pathogen.

• Immunity happens because next time you meet the pathogen the white blood cells quickly produce the correct antibody.

AQA Science © Nelson Thornes Ltd 2006  6

B1a 4.6 Immunity

Immune system

• You become ill the first time you meet a new pathogen.

• This is because it takes time to find the right antibody. With future infections your body destroys all the invaders before you can become ill.

AQA Science © Nelson Thornes Ltd 2006  7

B1a 4.6 Immunity

Vaccination.

• Some pathogens are dangerous because they can kill you before your body makes the right antibodies.

• These days we can protect ourselves against such diseases by immunisation (vaccination)

AQA Science © Nelson Thornes Ltd 2006  8

AQA Science © Nelson Thornes Ltd 2006  9

B1a 4.6 Immunity

This is how vaccines protect you against dangerous infectious diseases

Small amounts of dead or inactive pathogen are put into your body, often

by injection..

AQA Science © Nelson Thornes Ltd 2006  10

B1a 4.6 Immunity

This is how vaccines protect you against dangerous infectious diseases

The antigens in the vaccine stimulate your white blood cells into making antibodies.

AQA Science © Nelson Thornes Ltd 2006  11

B1a 4.6 Immunity

This is how vaccines protect you against dangerous infectious diseases

You are immune to future infections by the pathogen. This is because your body can respond rapidly and

make the correct antibodies as if you had already had the disease.

AQA Science © Nelson Thornes Ltd 2006  12

B1a 4.6 Immunity

This is how vaccines protect you against dangerous infectious diseases

B1a 4.6 Immunity

Key word splat.

AQA Science © Nelson Thornes Ltd 2006  13

antibody antigen

antibiotic Anti toxin

pathogen White blood cell

ingest