Today you got your first look at the peripheral nervous system, by learning how the afferent and efferent divisions provide information about, and responses to, pain.
It suggests that traumatic physical or psychological events, likely in combination with a genetic predisposition, may lead to that extreme response to pain and those other symptoms.
Using a group of patients who never feel pain, a study found that their pain matrix still activates in response to stimuli that healthy people find painful.