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how do sympathetic nervous system work and when?

The sympathetic nerves starts from the spinal column running towards the middle part of spinal cord in the lateral horn. It originates at the spinal cord’s first thoracic segment and extends to third lumbar segment. This nervous system is considered to have thoracolumbar outflow since the cells of these nerves originates in the lumbar and thoracic regions. The primary function of this nervous system is mobilization of the body’s nervous system due to fight or flight response. The messages through this system travels in a bidirectional flow, both afferent and efferent messages help in various functions of the body such as acceleration of heart rate, widening of bronchial passages to give increased oxygen, decreased movement of large intestine, piloerection, and perspiration.
It also helps in feeling sensations like cold, heat, and pain. The stress response of this system is also known as sympathoadrenal response since the preganglionic fibers of this nervous system activates secretion of adrenaline and noradrenaline which are commonly called epinephrine and norepinephrine. Since these fibers end in the medullar part of the adrenal gland, it secretes acetylcholine which also helps in activation.


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