CHAPTER 20The Autonomic Nervous System

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

ANS vs. Somatic NSANS vs. Somatic NS

Somatic Nervous System Conscious/voluntary branch of the Peripheral Nervous Conscious/voluntary branch of the Peripheral Nervous

SystemSystem Single motor neuron out to effectorsSingle motor neuron out to effectors Effectors Effectors –– skeletal muscleskeletal muscle

Autonomic Nervous Systemstem Involuntary branch of the Peripheral Nervous SystemInvoluntary branch of the Peripheral Nervous System Two motor neuronsTwo motor neurons

PreganglionicPreganglionic PostganglionicPostganglionic

Effectors Effectors –– smooth muscle and glandssmooth muscle and glands

Autonomic Nervous SystemAutonomic Nervous System

Sympathetic Division of the ANSSympathetic Division of the ANS Fight or FlightFight or Flight

Parasympathetic Division of the ANSParasympathetic Division of the ANSRest and DigestRest and Digest

Somatic NSSomatic NS

Sympathetic NS Sympathetic NS

Sympathetic NSSympathetic NS(special)(special)

ParasympatheticParasympatheticNSNS

20_0620_06 Origins of Pre & Post ganglionic Origins of Pre & Post ganglionic fibersfibers

Sympathetic NS Preganglionic fiber Preganglionic fiber –– Thoracolumbar region of Thoracolumbar region of

the spinal cordthe spinal cord Postganglionic fiber Postganglionic fiber –– Sympathetic Ganglion Sympathetic Ganglion

Chain or Collateral GanglionChain or Collateral Ganglion Parasympathetic NS

Preganglionic fiber Preganglionic fiber –– Craniosacral region of Craniosacral region of the CNSthe CNS

Postganglionic fiber Postganglionic fiber –– Terminal ganglia (in or Terminal ganglia (in or near effector organs)near effector organs)

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Length of Pre & Post ganglionic Length of Pre & Post ganglionic fibersfibers

Sympathetic NSPreganglionic fiber Preganglionic fiber –– ShortShortPostganglionic fiber Postganglionic fiber –– LongLong

Parasympathetic NSPreganglionic fiber Preganglionic fiber –– LongLongPostganglionic fiber Postganglionic fiber –– ShortShort

20_0220_02

20_0320_03 Type of Pre & Post ganlionic FibersType of Pre & Post ganlionic Fibers

Sympathetic NS Preganglionic fibers: Cholinergic (ACh Preganglionic fibers: Cholinergic (ACh

secreting)secreting) Postganglionic fibers: Adrenergic Postganglionic fibers: Adrenergic

(Norepinephrine secreting)(Norepinephrine secreting)

Parasympathetic NS Preganglionic fibers: Cholinergic (ACh Preganglionic fibers: Cholinergic (ACh

secreting)secreting) Postganglionic fibers: Cholinergic (ACh Postganglionic fibers: Cholinergic (ACh

secreting)secreting)

20_0620_06 Type of Receptors on PostType of Receptors on Post--ganlionic Neuronganlionic Neuron

Sympathetic NS Preganglionic fibers: Cholinergic (ACh Preganglionic fibers: Cholinergic (ACh

secreting)secreting) Postganglionic receptors: NicotinicPostganglionic receptors: Nicotinic

Parasympathetic NS Preganglionic fibers: Cholinergic (ACh Preganglionic fibers: Cholinergic (ACh

secreting)secreting) Postganglionic receptors: NicotinicPostganglionic receptors: Nicotinic

20_0620_06 Type of Receptors on EffectorType of Receptors on EffectorSympathetic NSPostganglionic fibers: Adrenergic Postganglionic fibers: Adrenergic

(Norepinephrine secreting)(Norepinephrine secreting)Effector receptors: AdrenergicEffector receptors: AdrenergicAlpha or Beta (1,2 or 3)Alpha or Beta (1,2 or 3)

Parasympathetic NSPostganglionic fibers: Cholinergic Postganglionic fibers: Cholinergic

(ACh secreting)(ACh secreting)Effector receptors: MuscarinicEffector receptors: Muscarinic

20_0620_06 Dominance & Types of DischargeDominance & Types of Discharge

Sympathetic NSFight or FlightFight or FlightFrequently a mass discharge of Frequently a mass discharge of

entire systementire systemParasympathetic NSRest and DigestRest and DigestUsually discrete organ activationUsually discrete organ activation