And if you're a bacterial cell hanging onto that splinter, don't think you're safe just because you're far from the blood stream and the white blood cells. You should see those cells slide through the blood vessel walls and wipe out invaders.

To learn more about white blood cells:

1. Go to the Your Body's Defenders WWW Sheet and print it.

2. Visit this Web site. Click "Ouch" to find out more.
    Anatomy of a Splinter

3. Visit this Web site. Then complete the WWW Sheet.
    Relative Size of Lymphocytes (White Blood Cells)

4. For more information, visit these Web sites. Scroll down and click the movie button.
    White blood cells FIND invaders (Chemotaxis)
    White blood cells EAT invaders (Phagocytosis)