The Immune System

The immune system is your body's army. It fights off germs like bacteria and viruses. When germs sneak in, special cells jump into action. They work hard to keep you healthy and strong.

How It Fights Germs

White blood cells are the main fighters in your immune system. They find germs and attack them. Your skin also helps by keeping most germs out. When you get a fever, your body is trying to cook the germs and kill them.

Red and white blood cells seen up close through a microscope.
Red and white blood cells seen up close through a microscope. (Bruce Wetzel (photographer). Harry Schaefer (photographer) / Wikimedia Commons)

Staying Healthy

Eating fruits and vegetables helps your immune system stay strong. Sleep also helps your body heal and fight germs. Washing your hands keeps germs from getting inside you. Vaccines teach your body how to fight certain sicknesses.

Fun Facts

  • Your body has about 25 billion white blood cells.
  • When you sneeze, germs can fly out at over 100 miles per hour.
  • Your skin is your biggest defense against germs.

Did You Know?

Your immune system remembers germs it has fought before. This is why you usually get chickenpox only once.