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The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. [4] The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system.
Each spinal nerve receives a branch called a gray ramus communicans (pl.: rami communicantes) from the adjacent paravertebral ganglion of the sympathetic trunk.The gray rami communicantes contain postganglionic nerve fibers of the sympathetic nervous system and are composed of largely unmyelinated neurons.
A sympatholytic (sympathoplegic) drug is a medication that opposes the downstream effects of postganglionic nerve firing in effector organs innervated by the sympathetic nervous system (SNS). [1] They are indicated for various functions; for example, they may be used as antihypertensives.
The sympathetic nervous system regulates the "fight or flight" responses. The parasympathetic nervous system regulates the "rest and digest" responses. The enteric nervous system innervates the viscera (gastrointestinal tract, pancreas, and gall bladder). The somatic nervous system consists of peripheral nerve fibers that send sensory ...
Another serious complication that can result from lesions above T6 is neurogenic shock, which results from an interruption in output from the sympathetic nervous system responsible for maintaining muscle tone in the blood vessels. [6] [50] Without the sympathetic input, the vessels relax and dilate.
The sympathoadrenal system is a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli. [1] When the body receives sensory information, the sympathetic nervous system sends a signal to preganglionic nerve fibers , which activate the ...
The sympathetic trunk is a fundamental part of the sympathetic nervous system, and part of the autonomic nervous system. It allows nerve fibres to travel to spinal nerves that are superior and inferior to the one in which they originated. Also, a number of nerves, such as most of the splanchnic nerves, arise directly from the trunks.
The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels, resulting in low blood pressure and thus not enough blood flow to the brain. [2] Diagnosis is based on the symptoms after ruling out other possible causes. [3] Recovery from a reflex syncope episode happens without specific treatment. [2]