How do pain relievers work? - George Zaidan 

Some people take aspirin or ibuprofen to treat everyday aches and pains, but how exactly do the different classes of pain relievers work? Learn about the basic physiology of how humans experience pain, and the mechanics of the medicines we've invented to block or circumvent that discomfor.  Link http://ed.ted.com/lessons/how-do-pain-relievers-work#watch