Not done the exam but agree with mad_jock. The dangers of panic and hyperventilation are well known to divers. Not sure that the body goes into shock though. Unconsciousness can occur because the low levels of carbon dioxide in the blood mean that the breathing reflex is not triggered. This is quite diffrerent from shock in the medical sense. Its also one of the big dangers for free divers, who will often pass out suddenly and often on the surface because the hyperventilation before the dive flushes the system of Co2.