Sympathetic nervous system is a principal division of the autonomic nervous system, academically defined by its role in mediating the "fight-or-flight" response. As a field of study, it investigates the neural pathways, neurotransmitters, receptors, and physiological adaptations that prepare the body for acute stress or physical exertion, holding significant importance in understanding stress physiology, energy mobilization, and the pathogenesis of various cardiovascular and metabolic disorders.