Immune System

This passage describes the job of the immune system in the human body.

Lexile Level: 800L

Categories: Sports & Health

Every day, the human body comes into contact with germs. The skin tries to keep these germs out of the body. If germs get past the skin and into the body, the immune system is ready to attack. The immune system is the body's defense system against these invaders. Its purpose is to destroy the invaders. It also remembers how to fight them in case they come back. "Headquarters" for the defenses are inside special tissues and organs. At headquarters, the body makes and trains white blood cells. White blood cells are the secret weapon for fighting invaders. Some white blood cells are trained to fight disease and infection. Other white blood cells move around the body and are always on the lookout for invaders. There are also white blood cells that stay in headquarters and leave only if they are needed. With this team of fighters, you're fully prepared to stay healthy!