Download MBBS Anatomy PPT 41 Autonomic Nervous System 2 Notes

Autonomic Nervous System

? A. Comparison of somatic and autonomic

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nervous systems

? B. Anatomy of autonomic motor pathways

1. Overview

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a. Preganglionic neurons
b. Autonomic ganglia
c. Postganglionic neurons

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? C. Physiological effects of ANS

1. ANS neurotransmitters
2. Parasympathetic and sympathetic

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responses

ANS regulates activities of cardiac muscle, smooth
muscle, and glands.

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?Structurally, ANS consists of two main components:

1. visceral afferent neurons

2. visceral efferent neurons

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?Functionally, the ANS operates:

1. without conscious control

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2. reflex arc dependent

3. medulla and hypothalamus over ride

Somatic & Autonomic Nervous Systems

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Somatic

Autonomic

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cutaneous receptors chemoreceptors
proprioceptors baroreceptors
special senses mechanoreceptors

may become conscious unconscious

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excitatory for skeletal excitatory or inhibitory for
muscles cardiac muscle, smooth

muscles, and glands

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single motor neuron two motor neurons

Somatic and Autonomic Efferent Pathways

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Overview of Autonomic Pathways
?Preganglionic neuron

?1. first of two autonomic motor neurons

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?2. cell body located in gray matter of spinal

cord (lateral column) or brain

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?Thoraco lumbar ? sympathetic & Craniosacral

?parasympathetic

?3. preganglionic axon passes from CNS in a

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spinal or cranial nerve

?4. axon terminates in a ganglion

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Overview of Autonomic Pathways

?Ganglion

?1. collection of nerve cell bodies located in

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a specific site outside CNS

?2. cell bodies give rise to postganglionic

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neurons

Overview of Autonomic Pathways

?Postganglionic neuron

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?1. second of two autonomic motor neurons

?2. cell body located in ganglion

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?3. postganglionic axon passes from ganglion

to effector Organ

?4. peripheral effector is either stimulated or

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inhibited


Sympathetic Nervous System

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?1. lateral gray horns (T1-L2)
?2. Thoracolumbar outflow

?3. ganglia

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a. sympathetic trunk (paravertebral)

b. Prevertebral (collateral)

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?4. preganglionic axons short

?5. postganglionic axons long

Sympathetic Nervous System

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Parasympathetic Nervous System

?1. lateral gray horns (S2-4)

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?2. cranial gray matter

(III, VII, IX, X)

?3. Craniosacral outflow

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?4. terminal ganglia

?5. preganglionic axons long

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?6. postganglionic axons short

Parasympathetic Nervous System

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Physiological Effects of ANS

? 1. dual (duel?) innervation

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? 2. different neurotransmitters
? 3. parasympathetic tone

ANS Neurotransmitters

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Cholinergic

Adrenergic

acetylcholine

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norepinephrine

all preganglionic neurons

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most postganglionic

all postganglionic parasympathetic & sympathetic neurons
few postganglionic sympathetic neurons

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acetylcholinesterase

catechol-O-methyl

transferase

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monoamine oxidase

Autonomic Nervous System - Neurotransmitters &
Receptors ? Sympathetic arm

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Autonomic Nervous System - Neurotransmitters &
Receptors ? Parasympathetic arm

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Sympathetic System

?1. energy expenditure system

?2. fight-or-flight response

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?3. dominates parasympathetic NS

?4. effects

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Parasympathetic System

?1. energy conservation-restoration

system

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?2. rest-and-recovery

?3. dominates sympathetic NS