Take a look at Out of Its Mind: Psychiatry in Crisis by J. A. Hobson & J. A. Leonard Perseus Publishing (2001). There is a fascinating detail about the functions of the amygdala in survival there: "The amygdala is like the hub of a wheel. It receives low-level inputs from sensory-specific regions of the thalamus, higher level information from sensory-specific cortex, and still higher level (sensory independent) information about the general situation from the hippocampal formation. Through such connections, the amygdala is able to process the emotional significance of individual stimuli as well as complex situations...the amygdala is, in essence, involved in the appraisal of emotional meaning. It is where trigger stimuli do their triggering."
Those things are said plays significant role and closely connected to stressful situations which engrave a conditioned memory trace in the amygdala, involved in those stressing conditions above. At least, a new look into our body can give useful things for understanding our own emotion, and hopefully manage it in better way.