1. The Autonomic Nervous System
Chapter 15
The Autonomic Nervous System

2. Autonomic Nervous System

3. Somatic and Autonomic Nervous System
Smooth and cardiac muscle and glands
Unconscious regulation
Target tissues stimulated or inhibited
Two synapses
Acetycholine by preganglionic neurons and ACh or norepinephrine by postganglionic neurons
Somatic
Skeletal muscle
Conscious and unconscious movement
Skeletal muscle contracts
Only one synapse
Acetylcholine the transmiter

4. Somatic versus Autonomic NS
Principles of Human Anatomy and Physiology, 11e

5. Principles of Human Anatomy and Physiology, 11e
Basic Anatomy of ANS
Preganglionic neuron
cell body in brain or spinal cord
axon is myelinated type B fiber that extends to autonomic ganglion
Postganglionic neuron
cell body lies outside the CNS in an autonomic ganglion
axon is unmyelinated type C fiber that terminates in a visceral effector
Principles of Human Anatomy and Physiology, 11e

6. Sympathetic vs. Parasympathetic NS
Principles of Human Anatomy and Physiology, 11e

7. AUTONOMIC NERVOUS SYSTEM
The output (efferent) part of the ANS is divided into two principal parts:
the sympathetic division
the parasympathetic division
Organs that receive impulses from both sympathetic and parasympathetic fibers are said to have dual innervation.
Table 15.1 summarizes the similarities and differences between the somatic and autonomic nervous systems.

8. Sympathetic ANS vs. Parasympathetic ANS
Principles of Human Anatomy and Physiology, 11e

9. Divisions of the ANS 2 major divisions parasympathetic sympathetic
Dual innervation
one speeds up organ
one slows down organ
Sympathetic NS increases heart rate
Parasympathetic NS decreases heart rate
Principles of Human Anatomy and Physiology, 11e

10. Divisions of the ANS 2 major divisions parasympathetic sympathetic
Dual innervation
one speeds up organ
one slows down organ
Sympathetic NS increases heart rate
Parasympathetic NS decreases heart rate
Principles of Human Anatomy and Physiology, 11e

11. Sympathetic Ganglia
These ganglia include the sympathetic trunk or vertebral chain or paravertebral ganglia that lie in a vertical row on either side of the vertebral column
Other sympathetic ganglia are the prevertebral or collateral ganglia that lie anterior to the spinal column and close to large abdominal arteries.
celiac
superior mesenteric
inferior mesenteric ganglia

12. Parasympathetic Ganglia
Parasympathetic ganglia are the terminal or intramural ganglia that are located very close to or actually within the wall of a visceral organ.
Examples of terminal ganglia include
ciliary,
pterygopalatine,
submandibular,
otic ganglia
Principles of Human Anatomy and Physiology, 11e

14. Sympathetic ANS vs. Parasympathetic ANS
Principles of Human Anatomy and Physiology, 11e

15. Dual Innervation, Autonomic Ganglia
Parasympathetic (craniosacral) division
preganglionic cell bodies in nuclei of 4 cranial nerves and the sacral spinal cord
Ganglia
terminal ganglia in wall of organ
Sympathetic (thoracolumbar) division
preganglionic cell bodies in thoracic and first 2 lumbar segments of spinal cord
Ganglia
trunk (chain) ganglia near vertebral bodies
prevertebral ganglia near large blood vessel in gut (celiac, superior mesenteric, inferior mesenteric)
Principles of Human Anatomy and Physiology, 11e

16. Autonomic Plexuses
These are tangled networks of sympathetic and parasympathetic neurons (Figure 15.4) which lie along major arteries.
Major autonomic plexuses include
cardiac,
pulmonary,
celiac,
superior mesenteric,
inferior mesenteric,
renal and
hypogastric
Principles of Human Anatomy and Physiology, 11e

18. Sympathetic Division
Preganglionic cell bodies in lateral horns of spinal cord T1-L2
Preganglionic axons pass through ventral roots to white rami communicantes to sympathetic chain ganglia
Four routes possible
Spinal nerves
Sympathetic nerves
Splanchnic nerves
Innervation to adrenal gland

19. Routes by Sympathetic Axons

20. Parasympathetic Division
Preganglionic cell bodies in nuclei of brainstem or lateral parts of spinal cord gray matter from S2-S4
Preganglionic axons from brain pass to ganglia through cranial nerves
Preganglionic axons from sacral region pass through pelvic nerves to ganglia
Preganglionic axons pass to terminal ganglia within wall of or near organ innervated

21. Enteric Nervous System
Consists of nerve plexuses within wall of digestive tract
Sources
Sensory neurons that connect the digestive tract to CNS
ANS motor neurons that connect CNS to digestive tract
Enteric neuron which are confined to enteric plexuses

22. Distribution of ANS Fibers
Sympathetic axons reach organs through
Spinal nerves
Head and neck nerve plexuses
Thoracic nerve plexuses
Abdominopelvic nerve plexuses
Parasympathetic axons reach organs through
Cranial nerves
Pelvic nerves

23. Physiology of ANS Neurotransmitters Receptors
Acetylcholine released by cholinergic neruons
Norepinephrine released by adrenergic neurons
Receptors
Cholinergic
Nicotinic and muscarinic
Adrenergic
Alpha and beta receptors

24. Location of ANS Receptors

25. Regulation of ANS
Autonomic reflexes control most of activity of visceral organs, glands, and blood vessels
Autonomic reflex activity influenced by hypothalamus and higher brain centers
Sympathetic and parasympathetic divisions influence activities of enteric nervous system through autonomic reflexes
Enteric nervous system can function independently of CNS through local reflexes

26. Autonomic Reflexes

27. Influence of Brain on Autonomic Functions

28. Functional Generalizations of ANS
Stimulatory versus inhibitory effects
Both divisions of ANS
Dual innervation
Most organs innervated by both
Either division alone or both working together can coordinate activities of different structures
Sympathetic produces more generalized effects
Prepares body for physical activity or flight-or-fight response
Parasympathetic more important for resting conditions
SLUDD: Salivation, lacrimation, urination, digestion, defecation

29. “Fight-or-Flight” Responses
Increased heart rate and force
Blood vessel dilation in skeletal and cardiac muscles
Dilation of air passageways
Energy sources availability increased
Glycogen to glucose
Fat cells break down triglycerides
Muscles generate heat, body temperature increases
Sweat gland activity increases
Decrease in nonessential organ activities