The autonomic nervous system (ANS) governs involuntary functions like heart rate, digestion, respiration, and more. It has two divisions - the sympathetic ("fight or flight") division which prepares the body for emergencies, and the parasympathetic ("rest and digest") division which conserves energy. The ANS is composed of preganglionic and postganglionic neurons. It is controlled by the hypothalamus and brainstem and can function independently at the spinal cord level for some parasympathetic functions like urination.

1. Nervous 3
Autonomic Nervous System
McKinley and O’Laughlin
Chapter 18

2. Introduction
 What part of the vertebrate nervous system
innervates smooth and cardiac muscle and
glandular tissues and governs involuntary,
vital functions?

3. The ANS affects the following:
 heart rate
 digestion
 respiration rate
 salivation
 perspiration
 diameter of the pupils
 micturition (urination)
 sexual arousal

4.  Whereas most of its actions are involuntary, some
actions of the ANS, such as breathing, work in
tandem with the conscious mind.

5. The ANS is:
 Purely motor (though some references
include visceral sensory as an arm of the
ANS)
 A functional, not anatomical, division
 Opposite is the somatic nervous system
 Mostly working beyond our conscious
awareness

6. Autonomic vs. Somatic
 If we follow a nerve impulse from the CNS
to an effector within the SNS, how many
motor neurons would be involved?
 If we follow a nerve impulse from the CNS
to an effector within the ANS, how many
motor neurons would be involved?

8. Autonomic vs. Somatic
 A motor neuron within the ANS that lies
between the CNS and a ganglion is what
type of neuron?
 Pre-ganglionic - myelinated
 A motor neuron within the ANS that lies
between a ganglion and an effector is what
type of neuron?
 Ganglionic - unmyelinated

9. Autonomic vs. Somatic
 What is the axon of a ganglionic neuron
with in the ANS?
 Post-ganglionic axon

10. ANS Divisions
 What are the 2 divisions of the ANS?
 Sympathetic division
 Parasympathetic division

11. ANS Divisions
 What division of the ANS is primarily
concerned with conserving energy and
replenishing nutrient stores and has been
nicknamed the “rest-and-digest” division?
 Parasympathetic division

12. ANS Divisions
 What division of the ANS is primarily
concerned with preparing the body for
emergencies and is often referred to as the
“fight-or-flight” division?
 Sympathetic division

13.  The parasympathetic division is sometimes
referred to as “craniosacral” because the
nerves arise from the brain stem (mainly
vagus) & sacral region
 The sympathetic division is sometimes
referred to as “thoracolumbar” because of
the sympathetic neurons in the spinal nerves
of these regions.

16. Parasympathetic Division
 What is another term for the
parasympathetic division?
 _________ division

17. Parasympathetic Division
 Where are the cell bodies of the
preganglionic neurons for the
parasympathetic division located?
 Brainstem
 S2-S4 (lateral gray matter of spinal cord)

18. Parasympathetic Division
 Where are the ganglia of the
parasympathetic division found?
 Terminal ganglia - close to target organ
 Intramural ganglia - within wall of target organ

20. Parasympathetic Division
 What cranial nerves carry parasympathetic
fibers?
 III Oculomotor
 VII Facial
 IX Glossopharyngeal
 X Vagus

21. Parasympathetic Division
 The parasympathetic division innervates
what structures through the oculomotor
nerve?
 Ciliary muscle
 Pupillary constrictor of iris
 Dilator controlled by sympathetic division

22. Parasympathetic Division
 The parasympathetic division innervates
what structures through the facial nerve?
 Submandibular and sublingual glands
 Lacrimal gland
 Glands of nasal cavity, mouth, and palate

23. Parasympathetic Division
 The parasympathetic division innervates
what structures through the
glossopharyngeal nerve?
 Parotid gland

24. Parasympathetic Division
 The parasympathetic division innervates
what structures through the vagus nerve?
 Thoracic and abdominal organs

26. Parasympathetic Division
 What specific regions of the spinal cord
house the cell bodies of the parasympathetic
division of the ANS?
 Lateral horns

27. Parasympathetic Division
 What nerves carry fibers of the
parasympathetic division of the ANS
through the pelvis?
 Pelvic splanchnic nerves
 What does ‘splanchnic’ mean?
 Visceral

29. Parasympathetic Effects
 Increase saliva production
 Constrict pupils
 Constrict airways
 Produce tears
 Increase GI motility
 Contract bladder
 Erect penis/clitoris

30. Sympathetic Division
 What is another term for the sympathetic
division?
 _____________ division
 From what regions of the CNS does the
sympathetic division arise?
 T1-L2 (lateral horns of spinal cord)

31. Sympathetic Division
 What part of spinal nerves do the
preganglionic sympathetic axons travel
within as they leave the lateral horn of the
spinal cord?
 Anterior root

32. Sympathetic Division
 What sympathetic ganglia lie on the left and
right sides of the vertebral column from T1-
L2?
 Sympathetic trunk ganglia
 Paravertebral ganglia
 What structure of the sympathetic division
has the appearance of a pearl necklace?
 Sympathetic trunk (ganglia and axons)

33. Sympathetic Division
 What clusters of ganglia of the sympathetic
division of the ANS lie within the neck?
 Cervical ganglia
 What are the connections between spinal
nerves and the sympathetic trunks?
 Rami communicantes

35. Sympathetic Division
 What structures carry preganglionic
sympathetic axons from the T1-L2 spinal
nerves to the sympathetic trunk?
 White rami
 What structures carry postganglionic
sympathetic axons from the sympathetic
trunk to the spinal nerves?
 Gray rami

38. Sympathetic Division
 What structures are composed of
preganglionic axons that do not synapse in a
sympathetic trunk ganglion?
 Splanchnic nerves
 Splanchnic nerves of the sympathetic
division of the ANS terminate in what
structures?
 Prevertebral (collateral) ganglia

39. Sympathetic Division
 What structures are singular rather than
paired, are anterior to the vertebral column,
and are located only in the abdominal
cavity?
 Prevertebral ganglia

40. Sympathetic Division
 List the 3 prevertebral ganglia
 Celiac
 Superior mesenteric
 Inferior mesenteric

42. Sympathetic Pathways
 What pathway is a postganglionic axon
within if it travels through a gray ramus that
is at the same level as the ganglionic neuron
to innervate blood vessels or arrector pili
muscles or sweat glands?
 Spinal nerve pathway

43. Sympathetic Pathways
 What pathway is a postganglionic axon
within if the preganglionic neuron synapses
with a ganglionic neuron in a sympathetic
trunk ganglion, but the postganglionic axon
does not leave the trunk via a gray ramus,
but instead extends away from the
sympathetic trunk ganglion and goes
directly to the effector organ?
 Postganglionic sympathetic nerve pathway

45. Sympathetic Pathways
 What pathway is a postganglionic axon
within if the preganglionic axon passes
through the sympathetic trunk ganglia
without synapsing and extends to the
prevertebral ganglia?
 Splanchnic nerve pathway

46. Sympathetic Pathways
 What pathway is a sympathetic axon within
if it goes to the adrenal medulla?
 Adrenal medulla pathway

48. Sympathetic Effects
 Pupil dilation
 Airway dilation
 Sweat production
 Mass activation response to stress
 Increased heart rate, blood pressure, breathing
rate and depth, dilate pupils, stimulate RAS

49. Autonomic Nervous System
 Usually both divisions of the ANS innervate
organs. Where does this dual innervation
not occur?
 Cutaneous region
 Includes peripheral blood vessels
 Sympathetic only

50. Autonomic Plexuses
 What are collections of sympathetic
postganglionic axons, parasympathetic
preganglionic axons, and some visceral
sensory axons?
 Autonomic plexuses

51. Autonomic Plexuses
 List the 5 autonomic plexuses
 Cardiac plexus
 Esophageal plexus
 Pulmonary plexus
 Abdominal plexus
 Hypogastric plexus

53. CNS Control of ANS
 What part of the CNS has the greatest
control over the ANS?
 Hypothalamus
 What part of the CNS holds nuclei which
have a great deal of influence over
autonomic function?
 Brain stem

55. CNS Control of ANS
 What division of the ANS may process and
control certain functions at the level of the
spinal cord without involvement of the
brain?
 Parasympathetic
 E.g. Defecation and urination

57.  How does the
parasympathetic
reflex for urination
relate to potty
training?

58. The End of Autonomic Nervous System
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