Fighting Back Your immune system has tools to destroy germs. Your skin is one of them. It has cells that warn your body when germs attack. Your skin also makes chemicals that kill germs. Another tool is mucus. Mucus is a


thin film of slime. It makes a trap in your nose. T e slimy trap catches germs. Hairs


in your nose try to sweep germs out. Coughing or sneezing can toss germs out of your body, too.


The Germ Police Got a scratch or cut? T en cover it quickly. Germs can get into your body through scratches and cuts. T ey go right into your bloodstream. If you ignore the scratch, then your white blood cells get to work. White blood cells float through


your blood. T ey’re looking for bacteria and viruses. Your body makes diff erent kinds


of white blood cells. One kind will rush to an open cut. It gobbles up as many germs as it can. Eventually, these blood cells die, though. Another kind of white blood cell


makes antibodies. Antibodies stop an infection. T is kind of blood cell makes antibodies that match only harmful germs. T ese cells move through your body looking only for those kinds of germs. Once the harmful germs are


found, a third kind of blood cell takes over. Some of these cells are fighters. T ey kill invading viruses. Some of them are like generals. T ey tell the fighter cells what to do.


Fun Fact: About 50 billion white blood cells fi ght diseases in your blood.


Mucus (yellow) clings to nose hairs (green). 14 NATIONAL GEOGRAPHIC EXPLORER


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