A group of platelets struggle to unload the materials needed to "fix" a road, referring to a blood vessel of the body. Red Blood Cell and White Blood Cell help them aside from their mission of finding the invading pneumococcus.
Ralphie's class enters his body to find out what is making him sick. His classmates find bacteria cells in his throat and watch the white blood cells battle the bacteria cells. This clip illustrates the function of white blood cells: to fight infection and disease.