To the naked eye, your body may not look like the site of much action, but take a closer look and you'll see the microscopic battles being waged every moment of every day, between our bodies' invaders and the systems that fight back.

Blood under 1000x magnification

Bacteria attack while blood cells in the mouth

Our skin

A human head louse rotating under a scanning electron microscope

Sperm under 1000x magnification

Killer T cell attacking cancer

Tick biting a man's leg

Hair

White blood cells attacking a parasite