Chapter 012

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 12:Autonomic Nervous System

Lesson 12-1 Objectives

• Describe the functions of the autonomicnervous system.

• Identify the two divisions of the autonomic nervous system.

• State the anatomical and functionaldifferences between the sympatheticand parasympathetic nervous systems.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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Autonomic Nervous System (ANS)

• Allows the organs to respond to changing body needs

• Carries out automatic and unconscious visceral responses

• Regulates organ function (visceral reflexes)– Examples: Pupillary response and blood pressure

reflex


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Visceral Reflex Pathway

• Activation of receptor• Transmission of sensory information to CNS• Processing of sensory information by CNS• Transmission of motor response to effector

organ(s)• Visceral response


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Autonomic Nervous System: Divisions

• Parasympathetic– Feed and breed– Craniosacral

• Sympathetic– Fight-or-flight– Thoracolumbar


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Sympathetic Reponses

• Fight-or-Flight Response– Heart rate and contractile strength increase.– Blood vessels constrict.– Blood pressure increases.– Bronchial tubes dilate. – Pupils dilate.– Adrenal medulla secretes epinephrine and

norepinephrine.– Excess sweating (diaphoresis)


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Parasympathetic Responses

• Feed-and-Breed Response– Heart rate decreases.– Blood pressure decreases.– Digestive tract stimulates motility and secretion.


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Autonomic Tone

• Sympathetics and parasympathetics continuously fire at a low level.

• Each system dominates in specific situations.– Resting heart rate: Parasympathetics – Vasomotor (blood vessel) tone: Sympathetics


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Lesson 12-2 Objectives

• Define cholinergic and adrenergic fibers.• Name the major neurotransmitters of the

autonomic nervous system.• Name and locate the cholinergic and

adrenergic receptors.• Explain the terms used to describe the effects

of drugs on autonomic receptors.


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Autonomic Neurons: Arrangement

• Arrangement of both sympathetic and parasympathetic fibers– Preganglionic fiber– Ganglion– Postganglionic

fiberCopyright © 2011, 2007 by Saunders,

an imprint of Elsevier Inc. All rights reserved.

10

Sympathetic Neurons

• Location of ganglia– Close to and parallel

to spinal cord– Paravertebral ganglia

• Naming of fibers – Preganglionic:

Cholinergic– Postganglionic:

AdrenergicCopyright © 2011, 2007 by Saunders,

an imprint of Elsevier Inc. All rights reserved.

11

Parasympathetic Neurons

• Location of ganglia– Near or in effector

organ

• Naming of fibers– Preganglionic:

Cholinergic– Postganglionic:

Cholinergic


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Fibers and Neurotransmitters

• Two neurotransmitters– ACh– Norepinephrine

• Two types of fibers– Cholinergic – Adrenergic


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Two Types of ANS Receptors

• Cholinergic– Muscarinic– Nicotinic (NN)

• Adrenergic– Alpha1

– Beta1 and beta2


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Cholinergic Receptors

• Muscarinic– Located on

effector organ of parasympathetics

• Nicotinic– NN (ganglia)

– NM (not autonomic)


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Adrenergic Receptors

• Alpha1

• Beta1 and beta2

• All adrenergic receptors located on effector organs of sympathetic nervous system


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Autonomic Pharmacology

• Agonist directly activates receptors– Alpha1-adrenergic agonist– Muscarinic agonist

• Antagonist prevents receptor activation– Beta2-adrenergic blocker – Muscarinic blocker (anticholinergic)


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Business

Chapter 012