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Chapter 19: The Autonomic Nervous System
BIO 218
Fall 2015
Somatic vs. Autonomic Nervous System
Table 19.1
Somatic & Autonomic Motor Relays
Fig. 19.1
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Autonomic Plexuses
In the thorax, abdomen, and pelvis, axons of
preganglionic neurons of both the sympathetic and parasympathetic divisions
(and sometimes autonomic ganglia and
axons of autonomic sensory neurons) form tangled networks called autonomic
plexuses, many of which lie along major
arteries.
Fig. 19.3
Divisions of the Autonomic Nervous
System (motor)
Sympathetic Nervous System – “Fight or Flight”
Parasympathetic Nervous System – “Rest and
Digest”
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Parasympathetic Division
• Referred to as the craniosacral division
• Long preganglionic fibers
• Terminal ganglia
• Short postganglionic fibers
Fig. 19.6
Fig. 19.1
Ciliary ganglion
Preganglionic fibers arise from CN III
(oculomoter)
Postganglionic fibers
innervate smooth muscle fibers in eyeball
Fig. 19.6
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Pterygopalatine ganglion
Preganglionic fibers arise from CN VII
(facial)
Postganglionic fibers
innervate nasal mucosa, palate, pharynx, lacrimal
glands
Fig. 19.6
Submandibular ganglion
Preganglionic fibers arise from CN VII
(facial)
Postganglionic fibers
innervate submandibular and sublingual salivary
glands
Fig. 19.6
Otic ganglion
Preganglionic fibers arise from CN IX
(glossopharyngeal)
Postganglionic fibers
innervate parotid salivary glands
Fig. 19.6
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Vagus nerve
Preganglionic fibers leaving the brain via
the vagus nerve account for 80% of the total craniosacral
outflow.
Axons end in terminal
ganglia in thorax and abdomen.
Fig. 19.6
Pelvic splanchnic nervesPreganglionic fibers
from anterior rami of
sacral nerves 2-4 form
the pelvic splanchnic
nerves.
Axons end in terminal
ganglia located within
the walls of the colon,
urinary bladder,
ureters, and
reproductive organs.
Postganglionic axons
supply smooth muscle
and glands.Fig. 19.6
Parasympathetic Nervous System
• A single parasympathetic preganglionic
fiber usually synapses with four or five postganglionic neurons.
• All of the postganglionic neurons supply a
single visceral effector.
• Parasympathetic responses localized to a single specific effector.
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Sympathetic Nervous System
Referred to as the
thoracolumbar division because
the preganglionic
neuronsarise from the
lateral horns of
thoracic and first two lumbar
segments.
Fig. 19.4
Fig. 19.1
Sympathetic Trunk Ganglia
Superior -
supplies head & heart
Middle – supplies heart
Inferior – supplies heart
Fig. 19.4
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Prevertebral Ganglia
Celiac
Superior mesentericInferior mesenteric
Aorticorenal
Renal
Fig. 19.4
Fig. 19.5
Sympathetic NS
• Postganglionic neurons arising from the symp.
trunk ganglia innervate organs above the diaphragm.
• Postganglionic neurons
arising from the prevertebral ganglia innervate organs below
the diaphragm.
Fig. 19.4
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Sympathetic Nervous System
• A single sympathetic preganglionic fiber
has many axon collaterals and can synapse with 20 or more postganglionic
neurons, which in turn terminate on
several effectors.
• Divergence allows the sympathetic input
to affect almost the entire body simultaneously.
Dual Innervation
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Copyright © 2010 Pearson Education, Inc.
15_table_04a
Table 19.3
Table 19.3
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How can the PNS and SNS have opposite effects at the level of a
specific target organ?
Autonomic neurons are classified based
on the neurotransmitter they produce and secrete.
Fig. 19.7
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Acetylcholine receptors
Fig. 19.7
Adrenergic Receptors
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Fig. 19.1
How are autonomic neurotransmitters
removed from a synapse?
1. Acetylcholinesterase
2. Presynaptic reuptake
3. Catechol-O-methyltransferase (COMT) or
monoamine oxidase (MAO)
Autonomic reflexes
What are the components of an autonomic
reflex arc?
• Blood pressure
• Digestion
• Defecation and urination
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Autonomic Control Center
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