Sympathetic Division

The Sympathetic Division is a branch of the autonomic nervous system that functions in coordination with the parasympathetic division to regulate involuntary bodily functions. It is responsible for mobilizing the body’s resources during times of stress or arousal, often referred to as the “fight-or-flight” response.


The sympathetic division originates from the thoracolumbar region of the spinal cord, extending from the first thoracic vertebra (T1) to the second lumbar vertebra (L2). It comprises two chains of ganglia located on either side of the spinal column, connected by nerve fibers.


The primary function of the sympathetic division is to prepare the body for action in stressful or threatening situations. It achieves this by increasing heartbeat, dilating blood vessels, and redistributing blood flow to the muscles. Additionally, it stimulates the release of adrenaline and noradrenaline hormones, enhances respiratory rate, and inhibits non-essential functions such as digestion.


The sympathetic division predominantly uses the neurotransmitter norepinephrine (noradrenaline) to transmit signals from postganglionic neurons to target organs. However, it also releases acetylcholine at specific synapses, depending on the location and type of receptor involved.

Physiological Responses

The activation of the sympathetic division elicits a range of physiological responses, including increased heart rate, elevated blood pressure, heightened alertness, enhanced sweating, and dilation of the pupils. These responses collectively prepare the body to deal with potential threats or stressors.

Clinical Implications

Malfunctions or dysregulation of the sympathetic division can lead to various health conditions. For example, excessive sympathetic activity may cause hypertension, while insufficient activity can result in conditions like orthostatic hypotension. Understanding the sympathetic division is crucial in diagnosing and treating such conditions.