Browse Lessons
Assign Lesson

Help Teaching subscribers can assign lessons to their students to review online!

Assign Lesson to Students

Share/Like This Page

The Immune System

The Immune System

Introduction: Your immune system protects you from being invaded by things that can make you sick. The skin is the first line of defense, keeping out many different intruders. However, when something enters the body through a cut or through the nose, mouth, or eyes, it is up to the immune system to fight it off. Sometimes it wins. Other times the intruder causes illness.

The primary component of the immune system is the white blood cell. In your body, you have different types of white blood cells (called leukocytes) that help to protect you from infection. T-cells and B-cells are the primary line of defense when a foreign substance enters. They attack the invader by either engulfing it or by disrupting its ability to reproduce. Therefore, these cells do not prevent the invader from entering the body, but rather keep it from taking hold and making more of itself, which prevents illness.

Some disease impact the immune system. HIV is known to repress a body's ability to fight off disease but killing off T-cells. When HIV develops into full-sledged AIDS, the body's defenses are at their lowest and even a common cold can turn into a deadly event.

Directions for this Lesson: Answer the practice questions and then watch the video to learn more about how the body protects itself.

Required Video:

Related Worksheets: