Section 5 The Peripheral Nervous System

1. D E F O R D
THE NERVOUS SYSTEM

2. PERIPHERAL
NERVOUS SYSTEM
2

3. PERIPHERAL NERVOUS SYSTEM
• The link between the neurons of
the CNS and the rest of the body;
all sensory information and motor
commands are carried by axons of
the PNS.
• Consists of:
• Spinal nerves
• Cranial nerves
3

4. SPINAL NERVES
• 31 pairs of spinal nerves exit from the
vertebral column
• Not named individually; grouped
according to level of the vertebral
column they arise from
• Except in the thoracic region, all
spinal nerves form complex networks
called plexuses which serve the
motor and sensory needs of the
limbs 4

5. DERMATOMES
• An area of skin that the
sensory nerve fibers of a
particular spinal nerve
innervate. All spinal nerves
except C1has dermatomes.
• Dermatomes are useful in
neurology for finding the
site of damage to the spine.
5

6. NERVES THAT ORIGINATE IN THE BRAIN
• 12 pairs of cranial nerves
• All cranial nerves serve the
head/neck except for the vagus
nerve
• Optic, olfactory &
vestibulocochlear are purely
sensory
• All others serve both sensory
and motor functions
6

7. 7
CRANIAL NERVES
I – smell
II – sight
III – moves eye, pupil shape/size
IV – moves eye
V – face sensation, chewing
VI – moves eye
VII – moves face, salivation
VIII – hearing, balance
IX – taste, swallowing
X – heart rate, digestion
XI – moves head
XII – moves tongue
Harry Potter Mnemonic:
On, On, On,TheyTraveled And FoundVoldemort Guarding Very Ancient Horcruxes

8. AUTONOMIC NERVOUS SYSTEM
• Motor subdivision of the PNS
that automatically controls
body activities
• Maintains homeostasis
• Includes neurons that control:
• cardiac muscle
• smooth muscle
• glands
heart rate
digestion
perspiration
pupillary dilation
8

9. Sympathetic
Division
Parasympathetic
Division
TWO DIVISIONS OF THE ANS
Both serve the same organs but counterbalance each
other to keep body systems running properly.
9

10. TWO DIVISIONS
Sympathetic
• Mobilizes the body
during extreme
situations
• Ex: fear, exercise, or
rage
Parasympathetic
• Allows us to unwind and
conserve energy
• Most active when the body is at
rest and not threatened in any
way
10

11. FIGHT-OR-FLIGHT
• The sympathetic nervous
system prepares the body
to either fight or run from a
threat
• Enables the body to cope
rapidly and vigorously with
situations that may disrupt
homeostasis
For example:
Dilation of blood vessels in skeletal
muscles prepares the body to run
faster or fight better
11

12. 12
EFFECTSONTHEBODY