Autonomic Nervous SystemAutonomic Nervous System

A. Comparison of somatic and autonomicA. Comparison of somatic and autonomic nervous systemsnervous systems

B. Anatomy of autonomic motor pathwaysB. Anatomy of autonomic motor pathways 1. Overview1. Overview a. Preganglionic neuronsa. Preganglionic neurons b. Autonomic gangliab. Autonomic ganglia c. Postganglionic neuronsc. Postganglionic neurons

C. Physiological effects of the ANSC. Physiological effects of the ANS 1. ANS neurotransmitters1. ANS neurotransmitters 2. Parasympathetic and sympathetic 2. Parasympathetic and sympathetic responsesresponses

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

Structurally, the ANS consists of two main Structurally, the ANS consists of two main components:components:

1. visceral afferent neurons1. visceral afferent neurons 2. visceral efferent neurons2. visceral efferent neurons

Functionally, the ANS operates:Functionally, the ANS operates: 1. without conscious control1. without conscious control 2. reflex arc dependent2. reflex arc dependent 3. medulla and hypothalamus override3. medulla and hypothalamus override

Comparison of Somatic and Comparison of Somatic and Autonomic Nervous SystemsAutonomic Nervous Systems

Somatic Somatic AutonomicAutonomic cutaneous receptors chemoreceptorscutaneous receptors chemoreceptors proprioceptors baroreceptorsproprioceptors baroreceptors special senses mechanoreceptorsspecial senses mechanoreceptors

may become conscious unconsciousmay become conscious unconscious

excitatory for skeletal excitatory or inhibitory forexcitatory for skeletal excitatory or inhibitory for muscles cardiac muscle, smoothmuscles cardiac muscle, smooth muscles, and glandsmuscles, and glands

single motor neuron two motor neuronssingle motor neuron two motor neurons

Comparison of Somatic and Comparison of Somatic and Autonomic Efferent PathwaysAutonomic Efferent Pathways

Sympathetic Versus Sympathetic Versus Parasympathetic DivisionsParasympathetic Divisions

Overview of Autonomic Overview of Autonomic PathwaysPathways

Preganglionic neuronPreganglionic neuron

1. first of the two autonomic motor 1. first of the two autonomic motor neuronsneurons2. cell body located in gray matter of 2. cell body located in gray matter of spinal cord or brainspinal cord or brain3. preganglionic axon passes from the 3. preganglionic axon passes from the CNS in a spinal or cranial nerveCNS in a spinal or cranial nerve4. axon terminates in a ganglion4. axon terminates in a ganglion

Overview of Autonomic Overview of Autonomic PathwaysPathways

GanglionGanglion

1. collection of nerve cell bodies located 1. collection of nerve cell bodies located in a specific site outside the CNSin a specific site outside the CNS

2. cell bodies give rise to postganglionic 2. cell bodies give rise to postganglionic neuronsneurons

Overview of Autonomic Overview of Autonomic PathwaysPathways

Postganglionic neuronPostganglionic neuron

1. second of the two autonomic motor 1. second of the two autonomic motor neuronsneurons2. cell body located in ganglion2. cell body located in ganglion3. postganglionic axon passes from the 3. postganglionic axon passes from the ganglion to the effectorganglion to the effector4. peripheral effector is either stimulated 4. peripheral effector is either stimulated or inhibitedor inhibited

Sympathetic Nervous SystemSympathetic Nervous System1. lateral gray horns (T1-L2)1. lateral gray horns (T1-L2)

2. thoracolumbar outflow2. thoracolumbar outflow

3. ganglia3. ganglia

a. sympathetic trunka. sympathetic trunk

(paravertebral)(paravertebral)

b. Prevertebral (collateral)b. Prevertebral (collateral)

4. preganglionic axons short4. preganglionic axons short

5. postganglionic axons long5. postganglionic axons long

Parasympathetic Nervous SystemParasympathetic Nervous System

1. lateral gray horns (S2-4)1. lateral gray horns (S2-4)

2. cranial gray matter2. cranial gray matter

(III, VII, IX, X) (III, VII, IX, X)

3. craniosacral outflow3. craniosacral outflow

4. terminal ganglia4. terminal ganglia

5. preganglionic axons long5. preganglionic axons long

6. postganglionic axons short6. postganglionic axons short

Physiological Effects of ANSPhysiological Effects of ANS

1. dual (duel?) innervation1. dual (duel?) innervation

2. different neurotransmitters2. different neurotransmitters

3. parasympathetic tone3. parasympathetic tone

ANS NeurotransmittersANS Neurotransmitters

CholinergicCholinergic AdrenergicAdrenergic

acetylcholine acetylcholine norepinephrine norepinephrine

all preganglionic neurons all preganglionic neurons most postganglionic most postganglionic all postganglionic parasympathetic neurons sympathetic neuronsall postganglionic parasympathetic neurons sympathetic neurons few postganglionic sympathetic neuronsfew postganglionic sympathetic neurons

acetylcholinesterase acetylcholinesterase catechol-O-methyl catechol-O-methyl transferasetransferase

monoamine oxidasemonoamine oxidase

Neurotransmitters and Receptors of the Neurotransmitters and Receptors of the Autonomic Nervous SystemAutonomic Nervous System

Sympathetic SystemSympathetic System

1. energy expenditure system1. energy expenditure system

2. fight-or-flight response2. fight-or-flight response

3. dominates parasympathetic NS3. dominates parasympathetic NS

4. effects4. effects

Parasympathetic SystemParasympathetic System

1. energy conservation-restoration 1. energy conservation-restoration systemsystem

2. rest-and-recovery2. rest-and-recovery

3. dominates sympathetic NS3. dominates sympathetic NS

4. SLUD4. SLUD