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What does the sympathetic nervous system do?

William B. Salt II., MD
Gastroenterology
Nerves that control the sympathetic branch of the autonomic nervous system (ANS) originate in the thoracic (chest) and lumbar (lower back) segments of the spinal cord.

The sympathetic nervous system is activated during emergencies -- or what you perceive or interpret to be emergencies. You become alert, vigilant, aroused, activated and prepared for action.

The sympathetic branch uses the neuropeptides epinephrine (also called adrenaline) and norepinephrine (also called noradrenaline) to activate your body's "fight or flight" stress response. Epinephrine and norepinephrine are collectively called "catecholamines." You can see epinephrine and norepinephrine as the "key" that leads to "fight or flight". When you have a "near miss" in your car, it is your sympathetic nervous system -- releasing epinephrine from your adrenal glands and norepinephrine from sympathetic nerve endings -- that causes you to be tremulous, sweaty and to feel that clutching sensation in your gut.
Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis (Mind-Body-Spirit Connection Series.)

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Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis (Mind-Body-Spirit Connection Series.)

Fast Facts on IBS: One in five people suffers from the frustrating symptoms of Irritable Bowel Syndrome (IBS). There is no simple answer--no pill, potion, or quick fix--that will cure IBS. But help...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.