Immune system cells attack a fl u virus (green).


You can’t see any of these battles. So how do you know if your immune system is working? It’s working well if you get better aſt er you’re sick. It’s also working if a cut heals. Your immune system is doing its job if you don’t get the same illness over and over. Your immune system doesn’t have to fight


alone. You can do things to help it. Wash your hands oſt en. T at way you’re less likely to catch germs from other people. Eat healthy foods. T at helps make your


body, and your immune system, strong. Exercise. Physical activity can help your body build antibodies. Finally, sleep. Not getting enough sleep can


weaken your immune system. By taking care of your body, you’ll keep your immune system in fi ghting form.


November–December 2013 15


antibody: a protein made by white blood cells to stop an infection or disease


bacterium: a tiny organism made up of one cell


immune system: the body system that protects you from disease and infection


unicellular: made of one cell virus: a tiny germ that can cause disease


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