Understanding Anesthesiology - The Global Regional Anesthesia ...

Sympathetic nervous system
The sympathetic system is mediated neurally, through the sympathetic chain, and humorally,
through the adrenal gland. Epinephrine and norepinephrine are the neurotransmitters
of the sympathetic nervous system in contrast to Ach which is the messenger of the parasympathetic
nervous system.
From the neural perspective, the sympathetic chain is comprised of presynaptic nerves exiting
the spinal cord through T1-L2; therefore, epidural or spinal blockade that involves any
or all of those levels will reduce sympathetic outflow. The sympathetic outflow to the heart
is at the level of T1-T4 and causes positive inotropy and chronotropy. The heart is not the
only way the the sympathetic nervous system effects the cardiovascular system: sympathetic
innervation along the entire distribution (T1-L2) controls the vascular tone of the blood vessels.
From the humoral perspective, the adrenal gland, when stimulated, exerts its effect by releasing
epinephrine and norepinephrine into the bloodstream.
Related Glossary Terms
Autonomic nervous system, Ephedrine Sulfate, Epidural analgesia, Epidural anesthesia, Epinephrine,
Four A’s of anesthesia, Pulse pressure, Shock, Spinal anesthesia, Vagus nerve
Index
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Chapter 3 - Regional Anesthesia
Chapter 3 - General Anesthesia
Chapter 5 - Obstetrical Anesthesia
Chapter 5 - Obstetrical Anesthesia
Chapter 6 - Opioid agonists and antagonists
Chapter 6 - Opioid agonists and antagonists
Chapter 6 - Opioid agonists and antagonists
Chapter 6 - Opioid agonists and antagonists
Chapter 6 - Opioid agonists and antagonists
Chapter 6 - Induction Agents
Chapter 6 - Inhaled Agents
Chapter 6 - Vasoactive Agents