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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