Science -- Your Future, Scotland's Future
SCI-FUN Roadshow Exhibits -- Body vs Germ
In this exhibit you learn about how your immune system defends your body against germs.

Your body is under constant attack by germs: bacteria, viruses, fungi and parasites. Germs use your body as their home, to live and reproduce in.

Infection by germs can waste our bodies' resources and poison us. Therefore our immune system fights off any germs that get into our bodies.

For germs to infect us, they must get past many different defences. If a germ can get past our skin (the best defence we have) it then faces the immune system. The immune system consists of a number of different cells that can swallow up, disable and dismatle germs.

Some of the cells in your immune system will attack anything they recognise as being from outside the body. Others are specific, and act against a particular infectious agent. It is these specific immune cells that remember previous infections and can be trained by vaccination.

Some of the symptoms we experience when ill are not due to germs themselves, but to our bodies' response to germs. For example, we vomit to expel germs from our stomachs, we have a fever to kill germs by heating and we have a runny nose as we wash away germs and dead cells in mucus.

Sometimes our immune system can mistake harmless things for germs, giving us an immune response when it isn't needed. Our bodies can launch an immune response against transplanted organs (called transplant rejection), our own tissues and organs (this is called an autoimmune disease) or against harmless foods or substances (allergies).

In the case of transplant rejection and autoimmune diseases, patients suffer due to damage and destruction of the organ or tissue in question. These patients can take immune-suppressant medication to dampen their immune system.

Mild allergies cause discomfort such as sneezing, rashes and weeping eyeswhen the person is exposed to the allergen (the substance they are allergic to). An extreme allergy can cause anaphylactic shock, where swelling of the air passages prevents the person from breathing and can cause death. Allergies are treated by avoiding the allergen, taking anti-histamines (which dampen the response) and carrying an emergency epi-pen in case of anaphylactic shock.

1 Germs live and ________ in your body.
2 What is our best defence against germs?
3 What do non-specific immune cells attack?
4 Why do we vomit when we have an infection?
5 What is an autoimmune disease?
6 Do you know of any common allergens?

1 Make a list of all the vaccinations you've had (you may need to ask your parents or guardians about this). Make a list of all the childhood diseases you've had (other than colds and 'flu). You are safe from all of these diseases.
2 Keep yourself infection-free. Learn how to correctly clean and protect wounds, how to avoid catching colds and other infectious diseases and how to cook food to prevent food poisoning.