The Immune System: The
Defenders
by Emmett Underhill

The main job of the immune
system is to protect our body from foreign invaders. The immune system
does this by sending out different types of cells that kill germs.
What are germs?
Germs are bacteria, fungi,
parasites, or viruses that make us sick. The cells of the immune system
can usually protect us from them.
These are viruses:
More viruses:

These are bacteria:

How do the immune system
cells protect us?
1. Special cells called
neutrophils and macrophages can eat and destroy germs. This is called
Phagocytosis. In this picture, a large Macropyhage cell on top, comes down
and surrounds and then starts to eat two germ cells.

Phagocytosis:

2. Special cells called
lymphocytes can attach to and kills virus infected cells. In this picture,
the smaller lymphocyte on the bottom is killing the bigger cell.

What does the immune
system look like?
These cells are produced in
our bone marrow, thymus, and spleen and circulate in our blood stream
looking for invaders.

Resources:
Books:
Cell Wars by Dr. Fran Balkwill and Mic Rolph. HarperCollins Pulbishers
(1990)
Internet:
newscenter.cancer.gov/sciencebehind/immune
www.cellsalive.com
Video:
The Magic School Bus: Inside Ralphie



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