1. The Autonomic Nervous System and Visceral Sensory Neurons
PART 1
The Autonomic Nervous System and Visceral Sensory Neurons

2. The ANS and Visceral Sensory Neurons
The ANS – a system of motor neurons
Remember, we’re on the motor side, visceral!
Innervates
Smooth muscle GI Tract, Respiratory Tract
Cardiac muscle - Heart
Glands – Endocrine
REGULATES: heart rate, blood pressure, digestion and urination
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3. The Autonomic Nervous System and Visceral Sensory Neurons
Figure 15.1
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4. Comparison of Autonomic and Somatic Motor Systems
One motor neuron extends from the CNS to skeletal muscle
Axons are well myelinated, conduct impulses rapidly
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5. Comparison of Autonomic and Somatic Motor Systems
Autonomic nervous system
Chain of two motor neurons
Preganglionic neuron
PostGanglionic neuron
Conduction is slower than somatic nervous system due to
Thinly myelinated or unmyelinated axons
Motor neuron synapses in a ganglion
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6. Autonomic and Somatic Motor Systems
Figure 15.2
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7. Divisions of the Autonomic Nervous System
Sympathetic and parasympathetic divisions
Chains of two motor neurons
Innervate mostly the same structures
Cause opposite effects
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8. Divisions of the Autonomic Nervous System
Sympathetic – “fight, flight, or fright”
Activated during EXTREME situations
Exercise
Excitement
Emergencies
Parasympathetic – “rest and digest”
Concerned with conserving energy
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9. Anatomical Differences in Sympathetic and Parasympathetic Divisions
Issue from different regions of the CNS
Sympathetic – also called the thoracolumbar division
Parasympathetic – also called the craniosacral division
Figure 15.3
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10. Anatomical Differences in Sympathetic and Parasympathetic Divisions
Length of postganglionic fibers
Sympathetic – long postganglionic fibers
Parasympathetic – short postganglionic fibers
Branching of axons
Sympathetic axons – highly branched
Influences many organs
Parasympathetic axons – few branches
Localized effect
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11. Anatomical Differences in Sympathetic and Parasympathetic Divisions
Neurotransmitter released by postganglionic axons
Sympathetic –
most release norepinephrine (adrenergic)
Parasympathetic –
release acetylcholine (cholinergic)
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12. Anatomical Differences in Sympathetic and Parasympathetic Divisions
Figure 15.4a
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13. Anatomical Differences in Sympathetic and Parasympathetic Divisions
Figure 15.4b
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14. Parasympathetic and Sympathetic Divisions
Table 15.1
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15. The Parasympathetic Division
Cranial outflow
Comes from the brain
Innervates
Organs of the head, neck, thorax, and abdomen
Sacral outflow
Innervation supplies
Remaining abdominal and pelvic organs
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16. The Parasympathetic Division
Figure 15.5
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17. Path of the Vagus Nerve Figure 15.6
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18. The Sympathetic Division
Basic organization
Issues from T1–L2
Preganglionic fibers form the lateral gray horn
Supplies visceral organs and structures of superficial body regions
Contains more ganglia than the parasympathetic division
Located on both sides of the vertebral column
Linked by short nerves into sympathetic trunks
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19. Sympathetic Trunk Ganglia
Figure 15.8
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20. Sympathetic Division of the ANS
Figure 15.7
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21. Sympathetic Pathways to the Body Periphery
Innervate
Sweat glands
Arrector pili muscles
Peripheral blood vessels
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22. Sympathetic Pathways to the Body Periphery
Figure 15.9
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23. The Role of the Adrenal Medulla in the Sympathetic Division
Major organ of the sympathetic nervous system
Constitutes largest sympathetic ganglia
Secretes great quantities of norepinephrine and adrenaline
Stimulated to secrete by preganglionic sympathetic fibers
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24. The Adrenal Medulla Figure 15.14
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25. Table 15.2 (1 of 3)
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26. Table 15.2 (2 of 3)
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27. Table 15.2 (3 of 3)
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28. Visceral Sensory Neurons
General visceral sensory neurons monitor
Stretch, temperature, chemical changes, and irritation
Cell bodies are located in the dorsal root ganglion
Visceral pain – perceived to be somatic in origin and is called  referred pain
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29. A Map of Referred Pain Figure 15.15
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