The amygdala is activated by internal or external events that appear to be threatening. This action releases neurochemicals that prepare the body for defensive action. Under the best of conditions, the amygdala works with parts of the cortex to connect the fear with cognition-‘it looks like a snake but it’s really a stick’- thus modulating the initial fear response.
Once the amygdala assesses the danger-either with or without help-the sympathetic branch of the nervous system (see past posts) is activated, speeding up the heart beat to get blood to the muscles to ready them for action, and rising blood sugar for increased energy. It is now that the adrenal glands release the hormone cortisol. Under normal circumstances, cortisol levels drop down to normal when the threat passes.