View full lesson: http://ed.ted.com/lessons/cell-vs-virus-a-battle-for-health-shannon-stiles

All living things are made of cells. In the human body, these highly efficient units are protected by layer upon layer of defense against icky invaders like the cold virus. Shannon Stiles takes a journey into the cell, introducing the microscopic arsenal of weapons and warriors that play a role in the battle for your health.

Lesson by Shannon Stiles, animation by Igor Coric.