autonomic nervous system

1. ivyanatomy.com
section 6, chapter 11
Autonomic
Nervous System

2. Autonomic Nervous System
• Functions without conscious effort
• Controls visceral activities
• Regulates smooth muscle, cardiac muscle, and glands
• Efferent fibers typically lead to ganglia outside of the CNS
• Two autonomic divisions regulate:
• Sympathetic division (speeds up)
• Prepares body for ‘fight or flight’ situations
• Parasympathetic division (slows down)
• Prepares body for ‘resting and digesting’ activities

3. Autonomic Nervous System
• The cell bodies of neurons that control effectors in the
ANS reside in ganglia outside the central nervous system.
Therefore, Autonomic pathways require and additional
motor neuron to reach the effector.
Figure 11.35 Motor pathways.
(a) Autonomic pathways
include 2 neurons between
the CNS and an effector. (b)
Somatic pathways usually
have a single neuron
between the CNS and an
effector.

4. Autonomic Pathway
1.
2.
3.
4.
5.
6.
Receptor
Sensory Neuron
Interneuron
Preganglionic Fiber
Postganglionic fiber
Effector

5. Sympathetic Division
Arise from thoracolumbar division of the spinal cord
• Location of preganglionic neurons
• Originate in lateral horns
• Preganglionic fibers leave spinal nerves
through white rami (myelinated fibers) and
enter sympathetic chain ganglia
(paravertebral ganglia)
• Postganglionic fibers extend from
sympathetic ganglia to visceral organs

6. Figure 11.37 Sympathetic fibers leave the spinal cord as
Figure 11.37 Sympathetic fibers leave the spinal cord as
preganglionic fibers, through the ventral roots of spinal
preganglionic fibers, through the ventral roots of spinal
nerves, enter sympathetic chain ganglia, and synapse with a
nerves, enter sympathetic chain ganglia, and synapse with a
postganglionic neuron that extends to visceral effectors.
postganglionic neuron that extends to visceral effectors.

7. Parasympathetic Division
• Ganglia are near or within various
organs = Terminal ganglia
• Preganglionic fibers arise from the brain and
sacral regions of the spinal cord.
• Short postganglionic fibers continue to
specific muscles or glands
Figure 11.39. The preganglionic fibers of the
Figure 11.39. The preganglionic fibers of the
parasympathetic division of the ANS arise from
parasympathetic division of the ANS arise from
the brain and sacral regions of the spinal cord.
the brain and sacral regions of the spinal cord.
Ganglia are located near the organs they
Ganglia are located near the organs they
serve.
serve.