Sympathetic
Sympathetic nervous system, is a division of the nervous system, besides the CNS or the PNS, whose major function is to produce localized adjustments which, for example, include sweating as a response to an increase in external temperature and the reflex adjustments of the cardiovascular system. It had been observed that under the conditions of stress, the entire sympathetic nervous system is activated and it meet the situation with increased arousal, resulting in an immediate widespread response termed as the fight-or-flight response.
This response is typically characterized by the release of large quantities of epinephrine from the adrenal gland that are located above the kidney, a momentary increase in heart rate, an increase in cardiac output, the vasodilation of the skeletal muscles, vasoconstriction of cutaneous and gastrointestinal organs, pupillary dilation, dialation of bronchi, and piloerection. The overall effect is to prepare the individual for upcoming imminent danger.