Your Immune System – Natural Born Killer: Crash Course Biology #132

Hank tells us about the team of deadly ninja assassins that is tasked with protecting our bodies from all the bad guys that want to kill us – also known as our immune system.

References
Campbell Biology, 9th ed.
http://faculty.stcc.edu/AandP/AP/AP2pages/Units18to20/blood/white.htm
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html