“Shock to the System” is the name of this season’s second episode — and here we thought the docs had had enough shocks for one lifetime. It looks like Cristina’s the one who is hardest hit tonight. We saw in the preview televised last week that she literally becomes paralyzed by fear in the OR, and a newly-released clip shows that her shock comes from a sudden loud noise, a reaction that is totally typical for someone suffering from posttraumatic stress disorder. When Derek asks Meredith if Cristina’s okay, Meredith flips out on him and berates him for driving so recklessly, telling him that she left his impulsive self in jail so that she’d know for a little while that he’s safe. Also — major spoiler alert — Meredith tells Derek about her miscarriage in tonight’s episode (and, you know, the fact that she was pregnant in the first place). In another clip, Mark talks to Callie about seizing the day and proposing to someone (read: Lexie), but Callie tells him not to skip steps like the two of them usually do with their respective squeezes. And finally, Bailey refuses to let Alex operate until he parts ways with the bullet in his chest. As usual, the actual kicks off tonight at 9 PM ET.