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ELAINE N. MARIEB

EIGHTH EDITION

7

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint Lecture Slide Presentation by Jerry L. Cook, Sam Houston University

ESSENTIALSOF HUMAN

ANATOMY& PHYSIOLOGY

PART D

The Nervous System

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Spinal NervesThere is a pair of spinal nerves at the level of

each vertebrae for a total of 31 pairsSpinal nerves are formed by the combinationof the ventral and dorsal roots of the spinal

cordSpinal nerves are named for the region fromwhich they arise

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Spinal Nerves

Figure 7.22a

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Anatomy of Spinal NervesSpinal nerves divide soonafter leaving the spinalcord

Dorsal rami servethe skin and musclesof the posterior trunk

Ventral rami forms acomplex of networks

(plexus) for theanterior

Figure 7.22b

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Autonomic Nervous SystemThe involuntary branch of the nervous system

Consists of only motor nerves

Divided into two divisions

Sympathetic divisionParasympathetic division

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Differences Between Somatic and Autonomic Nervous Systems

NervesSomatic one motor neuron

Autonomic preganglionic and postganglionic nerves

Effector organs

Somatic skeletal muscleAutonomic smooth muscle, cardiacmuscle, and glands

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Figure 7.24

Comparison of Somatic and AutonomicNervous Systems

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Anatomy of the Sympathetic DivisionOriginates from T 1 through L 2

Ganglia are at the sympathetic trunk (near thespinal cord)

Short pre-ganglionic neuron and long postganglionic neuron transmit impulse fromCNS to the effector

Norepinephrine and epinephrine areneurotransmitters to the effector organs

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Sympathetic Pathways

Figure 7.26

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Anatomy of the Parasympathetic DivisionOriginates from the brain stem and S 1 through

S4 Terminal ganglia are at the effector organs

Always uses acetylcholine as aneurotransmitter

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Autonomic FunctioningSympathetic fight -or- flight

Response to unusual stimulus

Takes over to increase activities

Remember as the E division = exercise,excitement, emergency, andembarrassment

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Development Aspects of the NervousSystem

The nervous system is formed during the firstmonth of embryonic development

Any maternal infection can have extremely

harmful effectsThe hypothalamus is one of the last areas ofthe brain to develop

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Development Aspects of the NervousSystem

No more neurons are formed after birth, butgrowth and maturation continues for severalyears

The brain reaches maximum weight as ayoung adult