Immunity

Learning Objective: Understand how the immune system is

involved in fighting disease

Starter: Name the different types of blood cell,

which ones help fight disease?

How are microbes passed along?

through the air through water by eating the microbes especially from

contaminated hands by touching through animals

Microbes: our defence against themOur bodies have many defence mechanisms against invading microbes:

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

The skin acts as a barrier

Stomach produces stomach acid

Tears contain an enzyme that kills bacteria

Fighting diseaseIf microbes do enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS:

White blood cells do 3 things:

1) They eat the microbe

2) They produce antibodies to neutralise the microbe

3) They produce antitoxins to neutralise the poisons produced by microbes

Phagocyte engulfs microbe – animation

Animation

Lymphocytes and antibodies – animation

Animation

Producing antibodies

Step 1: The white blood cell “sees” the antigen (microbe)

Step 2: The cell produces antibodies to “fit” the antigen

Step 3: The antibodies fit onto the antigens and cause them to “clump”

Step 4: The antigens are “eaten” by the white blood cells

You’re going down

Role Play

Work in groups of four or five. You have 10 minutes to work on a short

play, to last about 2 minutes, based on the white blood cells and how the antibody fights microbes.

A Microbe multiplies and creates illness.

B Microbe enters body.

C Body responds slowly.

D Body responds quickly. Microbe is killed before it has a chance to multiply and cause illness.

E Microbe enters body.

F Body produces enough antibodies and white blood cells to kill invading microbe. As microbe dies the symptoms disappear.

E Microbe enters body.

C Body responds slowly.

A Microbe multiplies and creates illness.

F Body produces enough antibodies and whiteblood cells to kill invading microbe. As microbe diesthe symptoms disappear.

B Microbe enters body.

D Body responds quickly. Microbe is killed before it has a chance to multiply and cause illness.

8C Vaccination

Put these events into the right order.

Multiple-choice quiz

Immunity

Learning Objective: Understand how the immune system is

involved in fighting disease