Dedicated To: Mr. Becerra

About the Author: Emaline Edson is a 9th grade student at Collegiate School of Medicine and Bio-science. She enjoys writing books about Billy. Billy takes on many different forms throughout the extended series.

Today is Billy's first day of school. He attends Bacteria Academy!

His teacher's name is Ms. Jordan. She will teach him about the immune system and all it can do.

Sometimes people get sick! Bodies must react in order to keep them safe. Non-specific defense does not target specific pathogens. Organs such as the skin are the first line of defense against bacteria. Skin is nearly a impenetrable barrier to keep antigens out!

Specific defense targets certain antigens. Their job is to protect the body against these specific molecules.

Antigens are foreign materials in the body that cause immune responses. A body's immune system must work to ensure that these antigens do not negatively affect the body.

Many cells are involved in protecting against antigens. B-cells, T-cells, phagocytes, and antibodies all play important roles. Antibodies neutralize pathogens. They prevent antigens from entering and damaging cells. Phagocytes ingest harmful antigens by engulfing and absorbing other small cells and particles. This process is called phagocytosis.

Antibodies chemically combine with substances that are easily recognized by the body. They are created in response to the presence of antigens. They counteract these antigens to protect the body from infection and disease.