Transcript The Peripheral Nervous System The P.N.S.

The
Nervous
System
Video Review Neurons 1
Fun Video Intro
Video Review Systems 2
The Peripheral
Nervous
System
The P.N.S.
Peripheral Nervous System
•
Somatic Nervous System
(SNS)
– Sensory neurons (for in/outside of the body)
– Motor nerves
– Messages between brain and body
- CONTROLS VOLUNTARY MUSCLES
•
Autonomic Nervous System
(ANS)
– Controls organs and some muscles
- CONTROLS INVOLUNTARY MUSCLES
Peripheral Nervous System
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The part of the neuron
that actually sends the
impulse is the cell’s
axon; the axons carry
the messages from one
nerve to the next.
The PNS is made up:
- 12 pairs of Cranial nerves
Found in the Skull
- 31 pairs of Spinal nerves
Found in the Spinal Cord.
Spinal Nerves
Spinal Nerves carry:
- motor (leg muscles),
- sensory (touch), and
-autonomic (heart, diaphragm)
signals between the spinal cord
and the body.
Cranial Nerves
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Cranial nerves are
nerves that emerge
directly from the
brain, in contrast to
spinal nerves.
They are “wired
directly to the brain.
Sight, Sound,
Smell.
Types of Nerves
Sensory nerves: carry information from
the sensory organs towards the C.N.S.
Motor nerves: carry information from
the C.N.S. to muscles and organs.
Motor vs. Sensory Nerves
Neuron Impulse Video
Motor nerves send
information from the
brain to the muscles.
Foot feels
something in
your boot.
Sensor sends
message to
brain
Sensory nerves send
information from the
sensory organs to the
brain.
Brain sends
appropriate info
to deal with
situation.
???
Motor Nerves carry messages concerning
voluntary movements from the brain to
the muscles.
Motor nerve:
Starts: In the brain;
Ends: At the muscle.
It is ONEWAY to
the muscle.
The Sensory Nerves relay to the brain
information that originates OUTSIDE the body
and is registered by the five senses.
Sensory nerve:
Start: Sense Receptor
End: Brain
It is ONEWAY to the
Brain.
Reflex Responses
The spinal cord serves as the
body’s reflex centre.
•
Reflex: An involuntary act that
results when a nerve impulse is sent
out by the spinal cord in response to
an unexpected stimulus.
You accidentally touch the burner
on your stove at home….
What happens?
You automatically pull your hand away.
HOW DOES THIS HAPPEN?
Reflex Response
1) The touch receptors in your hand relay
information to the spinal cord in the form of a
nerve impulse.
2) BUT this nerve impulse doesn’t get sent to the
brain. WHY?
- Because it would take too long and this
situation is urgent.
3) Instead, a nerve impulse is commanded from
the spinal cord to the hand muscles, telling
them to draw away.
- Processing the information at level of the
spinal cord instead of the brain allows the
response to occur faster.
Question:
If your knee’s reflexes are slow, or erratic,
what could that signify?
Consequences of Damage to
Nerve Cells
A. The nerve does not regenerate itself.
B. The transmission of impulses may
diminish or stop.
C. Interpretation of the impulse may be
distorted, interrupted, or only partially
completed.
Review Questions- PNS
1) What are the 2 divisions of the peripheral
nervous system and how are the different?
2) What two types of nerves exist and what
are 2 differences between them?
3) What 3 types of neurons are involved in
reflex responses and in what order do
nerve impulses travel through them?
4) What is the difference between a voluntary
movement such as walking and an
involuntary movement such as a reflex
response?
5) What could are consequences of nerve
damage?
Review Answers- PNS
1) What are the 2 divisions of the
peripheral nervous system and how
are they different?
The somatic nervous system includes
motor nerves that control voluntary
(skeletal) muscles and sensory nerves.
The autonomic nervous system includes
motor nerves that control involuntary
muscles (cardiac and smooth) and sensory
nerves.
2) What is a nerve?
A nerve is a bundle of nerve cell axons. The
other parts of nerve cells are not included in
nerves.
3) What two types of nerves exist and what
are 2 differences between them?
1) Sensory Nerves:
- transmit sensory information
from sensory organs to the CNS.
- allow you to perceive light,
sound, touch, smell and taste.
2) motor nerves:
- transmit information from the
CNS down to the muscles and
organs
- allow you to move
3) What 3 types of neurons are involved in
reflex responses and in what order do
nerve impulses travel through them?
1- Sensory neuron
2- Interneuron
3- Motor neuron
4) What is the difference between a
voluntary movement such as walking and
an involuntary movement such as a reflex
response?
- Voluntary movements get processed
by the brain, whereas involuntary
movements only get sent to the spinal
cord and don’t reach the brain.
5) What could are consequences of nerve
damage?
– The nerve might regenerate or might grow
back but not become functional.
– The transmission of nerve impulses may
diminish or stop.
– Interpretation of the impulse may be
distorted, interrupted, or only partially
completed.
All of these consequences will result in
motor and sensory impairments.
Review Questions - CNS
1) What are the main parts of the central
nervous system?
-brain, spinal cord
2) What is the brain?
The brain is the main organ of the CNS. It
is composed of nearly 100 billion nerve
cells which are folded together in order to
fit inside the cranium.
3) What are the 3 major structures of the
brain?
- cerebrum, cerebellum, brainstem
Review Questions - CNS
1) What are the main parts of the central
nervous system?
2) What is the brain?
3) What are the 3 major structures of the
brain?
4) What are the 4 different layers of protection
of the brain?
5) What functions are controlled by the left
cerebral hemisphere?
6) What functions are controlled by the right
cerebral hemisphere?
7) What did the study of Phineas Gage teach
us about the brain?
8) What are the different lobes of the cerebral
cortex and what are their functions?
9) What is the difference between white matter
and grey matter?
10) Who is Wilder Penfield and how did he
contribute to our understanding of the brain?
11) What is the function of the cerebellum?
12) What parts of your body does the
cerebellum communicate with?
13) What is the function of the brainstem?
14) What is the function of the spinal cord?
15) What protects the spinal cord?
16) What is a consequence of damage to
the spinal cord?
17) What 3 things can you do to improve
the power of you brain?