The sympathetic system readies the individual for action. We call this function ergotropic. Classically, it is assumed to implement the fight or flight response. This system predominates during the day and in wakefulness.

The part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands (such as salivary glands and sweat glands). One part of the autonomic nervous system helps the body rest, relax, and digest food and another part helps a person fight or take flight in an emergency. Also called ANS and involuntary nervous system.

The sympathetic division regulates the use of metabolic resources and coordinating the emergency response of the body to potentially life-threatening situations (“fight or flight”).

The general response to both physical and psychological stress is activation of the sympathetic nervous system with inhibition of the parasympathetic nervous system. When stress becomes severe or uncontrolled, then adrenomedullary release of epinephrine ensues. As stress increases even further, then CRF not only activates the sympathetic nervous system but leads to the release of adrenocorticotropic hormone and adrenocortical steroids. Sympathetic nervous stimulaton to the muscles activates vasoconstriction and increases peripheral vascular resistance.

The sympathetic nervous system is best thought of as the fight or flight system. It rapidly mobilizes key bodily systems in times of emergency or stress, preparing the body for action by raising blood pressure, relaxing and opening airways, mobilizing energy sources, and temporarily shutting down digestion. Most importantly, it increases blood flow to muscles by shutting down blood flow to the skin and intestines.

The overall function of the sympathetic nervous system is to prime the body for action. The preganglionic neurons of the sympathetic nervous system originate in the spinal cord segments T1 to L3, the thoracolumbar spinal cord. The location of the autonomic ganglia is paravertebral or prevertebral, therefore the preganglionic axons are short, differently from the parasympathetic system. Sympathetic preganglionic neurons of the sympathetic nervous system are always cholinergic; postganglionic neurons instead are adrenergic, releasing only norepinephrine, except for the cholinergic eccrine sweat glands.

The sympathetic system controls the fight-or-flight reactions during emergencies by increasing the sympathetic outflow to the heart and other viscera.

the sympathetic nervous system can be considered a fundamental factor in the regulation of food intake and body weight. The sympathetic influence on this regulation is exerted by an influence on body temperature; this is in accord with the “thermoregulatory hypothesis” of food intake.

A branch of the autonomic nervous system responsible for mobilizing the body’s energy and resources during times of stress and arousal.

The sympathetic division stimulates those activities that are mobilized by the organism during emergency and stress situations, the so called “fight, fright, and flight” responses. These include acceleration of the rate and force of the heartbeat, increase in the concentration of blood sugar, and increase in blood pressure.The sympathetic division is also called the thoracolumbar or adrenergic system because (1) its preganglionic fibers emerge from all thoracic and the upper two lumbar levels (T1 through L2) and (2) the neurosecretory transmitter released by the postganglionic fibers in most loci is norepinephrine, also known as noradrenalin.

The sympathetic nervous system (SNS) is one of two main branches or subsystems of the autonomic nervous system (ANS). It originates in the thoracic and upper lumbar segments of the spinal cord and commonly – but not always – yields peripheral adjustments that are complementary to those produced by its counterpart, the parasympathetic nervous system (PNS).

The part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate.

The sympathetic nervous system, sometimes abbreviated as SNS, is a component of the autonomic nervous system—the portion of the nervous system largely concerned with regulating automatic functions such as heart rate and digestion. Although commonly regarded as the portion of the nervous system that instigates the fight or flight response, the sympathetic nervous system also fulfills a constant role in regulating homeostasis—the maintenance of relatively consistent internal states.The sympathetic nervous system’s two primary functions are regulating homeostasis and instigating the fight or flight response. During times of stress, the sympathetic nervous system can dilate the pupils, elevate the heart rate, increase sweating, and elevate the blood pressure. The neurotransmitters adrenaline and noradrenaline are heavily implicated in the fight or flight response.During normal bodily functions, the SNS maintains homeostasis by maintaining a relatively consistent heart rate and blood pressure. People suffering from prolonged stress may experience constant activation of the sympathetic nervous system. This can lead to health problems such as depressed immunity and prolonged illness. It may also contribute to the development of mental health conditions such as anxiety, depression, posttraumatic stress, and hyper-reactivity.

The sympathetic system is catabolic, meaning that it burns energy. It is the one involved in the fight-or-flight response. If you remember this, most of the effects of the sympathetic nervous system make sense. The sympathetic nervous system is also called the thoracolumbar system because the ganglia are located lateral to the vertebral column in the thoracic and lumbar regions. In addition, because the ganglia are fixed along the back, the postganglionic fibers can be quite long. Within the sympathetic system the preganglionic axons form synapses with many postganglionic cells, thus giving this system a widespread action. Note that this is consistent with the fight-or-flight response.

The sympathetic system controls “fight-or-flight” responses. In other words, this system prepares the body for strenuous physical activity.

The Flight, Fight, Fright system, served by the sympathetic trunk in a rope ladder system of ganglia next to and in front of the spinal column (terminology: paravertebral and prevertebral respectively), with motor cells in the spinal cord from the level of the lower cervical to the upper lumbar segments.

The sympathetic, or thoracolumbar, part of the autonomic system comprises the preganglionic fibers that issue from the thoracic and upper lumbar levels of the spinal cord. These fibers reach spinal nerves by way of ventral roots and then leave the spinal nerves, reaching adjacent ganglia by way of rami communicantes (see fig. 3-2). These ganglia are contained in long nerve strands, the sympathetic trunks, one on each side of the vertebral column, extending from the base of the skull to the coccyx. Some preganglionic fibers synapse in ganglia that are studded along this nerve trunk, others continue to ganglia located anterior to the vertebrae, along the aorta (prevertebral or aortic plexuses), and still others synapse with cells in the medulla of the suprarenal (adrenal) glands. The postganglionic fibers either go directly to adjacent viscera and blood vessels or return to spinal nerves by way of other rami communicantes and, in the area of distribution of these nerves, supply the skin with (1) secretory fibers to sweat glands, (2) motor fibers to smooth muscle attached to hair follicles (arrectores pilorum), and (3) vasomotor fibers to the blood vessels of the limbs. The sympathetic system is an important part of the mechanism of reaction to stress.

In general, the sympathetic system often mediates the response of the body to stress by speeding up heart rate, increasing blood pressure, and mobilizing the body’s energy stores for an emergency response.

The branch of the autonomic nervous system that is involved in coordinating the activities of the body’s organs for fight-or-flight responses.