Physiologic Anatomy of the
Sympathetic Nervous System
Visceral motor neuron (preganglionic) located in the
(intermedio)lateral horn of the spinal cord from T-1 to
L-2.
Axons travel to ganglionic
neuron via 1 of 3 paths:
1. enter the sympathetic
chain via the white ramus
and terminate there or
ascend or descend a few
segments before
terminating
2. enter via the white ramus
and exit via a splanchnic
nerve and terminate in a
prevertebral (collateral)
ganglion
3. Enter via the white ramus
and exit via a splanchnic nerve
and terminate in the adrenal
medulla
Figure 60-2; Guyton & Hall
Sympathetic
Nervous System
Figure 60-1;
Guyton & Hall
Sympathetic Organization
Sympathetic Chain
Figure 16.4a
Collateral Ganglia
Adrenal Gland
Sympathetic Distribution
Parasympathetic
Nervous System
Figure 60-3;
Guyton & Hall
Parasympathetic Organization
Parasympathetic Distribution
Neurotransmitters
Receptors of the Autonomic
Nervous System
adrenergic receptors
sympathetic
preganglionic neuron
postganglionic neuron
parasympathetic
nicotinic receptors
muscarinic receptors
Pharmacology of the Sympathetic
Nervous System
• adrenergic or sympathomimetic drugs act like
norepi and epi
• these drugs have an effect which is much more
prolonged than that of either norepi or epi
– isoproterenol stimulates both beta1 and beta2 receptors
(e.g. increases heart rate)
– albuterol stimulates only beta2 receptors (e.g.
bronchodilation)
• some drugs act indirectly by increasing the release
of norepi from its storage terminals
– amphetamine
Pharmacology of the Sympathetic
Nervous System
Example - drugs that block the effect of
norepi and epi
• beta blockers
– beta1 - metoprolol
Pharmacology of the
Parasympathetic Nervous System
• parasympathomimetic drugs
– nicotine
• activates nicotinic receptors
• cholinesterase inhibitors
– neostigmine
• potentiates the effect of acetylcholine
• antimuscarinic drugs
– atropine
• blocks the effect of acetylcholine on effector cells