Immune System Questions

White Blood Cell Credit: Bruce Wetzel and Harry Schaefer/National Cancer Institute

The immune system is the body's natural defense mechanism. It protects us from invaders that we can't see, like viruses and bacteria.

The immune system uses two types of defense mechanisms depending on the threat to the body. Nonspecific defense mechanisms provide the first line of defense. In cases where microorganisms get through the primary deterrents, there are back-up systems called specific defense mechanisms.

Do you know which type of immunity protects the body from its own cancerous cells? Test your knowledge of the immune system. Take the Immune System Quiz!

Learn more about the immune system:

• Immune System
  
• Organ Systems