Tony Stark: [seeing wires running out of his chest] What the hell did you do to me?

Yinsen: What I *did* was save your life. That is an electromagnet, connected to a car battery. I removed as much shrapnel from your chest as I could, but there are still some pieces left. I've seen plenty of injuries like that. We call those casualties with them "the Walking Dead," because in a week they're dead. The magnet should prevent them from reaching your heart.