Transcript Peripheral Nervous System

Peripheral Nervous System
Sections 14 and 15
READ TONIGHT!!!
General Info of PNS
All nerves that branch off the CNS and connect
to other body parts.
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Cranial nerves – 12 pairs
Spinal nerves – 31 pairs
Functions:
To receive stimulus input and send to
CNS.
To relay the response from the CNS
to the appropriate effector organ.
Nerve
Anatomy
of the
PNS
Cranial Nerves
• Of the 12 pairs, here are some important
ones to know:
#1 – Olfactory = smell afferent
#2 – Optic = vision afferent
#8 – Vestibulocochlear = hearing/balance
afferent
#10 – Vagus = parasympathetic regulation
of heart, lungs, BV, digestive tract
Peripheral Nervous System
PNS
Motor
(Efferent)
Sensory
(Afferent)
Somatic
Skin and
special senses
Somatic
(Voluntary)
Visceral
Skeletal
Muscles
Autonomic
(Involuntary)
Sympathetic
Parasympathetic
Motor: Somatic nervous system
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All voluntary or conscious activities
Nerves connect to skeletal muscles
Thick myelination, fastest impulses
Pathways have one motor neuron to
muscle cells. (no synapses with other
neurons outside CNS)
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Neurotransmitter: Acetylcholine
Autonomic nervous system
- All involuntary or unconscious activities.
- Maintains internal environment
- Nerves connect to cardiac, smooth muscle or
glands
- Pathways have two neurons synapsing at a
ganglia before effector.
- 1st neuron is lightly myelinated; 2nd neuron is
unmyelinated.
- Neurotransmitters: Acetylcholine or
Norepinephrine
- Two divisions counterbalance each other:
Sympathetic and Parasympathetic
Sympathetic
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prepares for energy-expenditure,
excitement or stressful situations
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"fight" or take "flight“.
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Nerve fibers originate from the thoracic
and lumbar regions of spinal cord.
Short Pre and Long postganglionic fibers
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Parasympathetic
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Stimulated during calm and relaxing
situations
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"rest" and "digest" .
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Nerve fibers originate from the brain and
sacral region.
Long preganglionic fibers and short post
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Which pathway is
responsible here?
Sympathetic or Parasympathetic
Division of the ANS are
distinguished by:
1. Unique origin sites
a. Sacrocranial vs. Thoracolumbar
2. Different lengths of their fibers
a. Preganglionic (long – P, short – S)
b. Postganglionic (long – S, short – P)
3. Location of their ganglia
a. P – close to effector
b. S – close to spinal cord