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The Nervous System:
Master Control
Explore: How do you keep you
balance??
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(Balance Beam / marbles)
What were some of the things you had to
watch out for??
What kinds of body adjustments do you
have to make to keep yourself in balance?
Explore: How do you keep you balance??
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Think of a sport. (bicycling / ice skating /
ballet / etc):
describe the importance of maintaining
balance when performing this sport.
8-1: The role of your nervous system
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The body system that made adjustments
for your balancing acts is called your
nervous system.
The nervous system is composed of the
brain, spinal cord and all the nerves that
connect those 2 structures with other parts
of the body.
The nervous system has 3 major functions.
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First is receives information about the
environment and the other parts of the
body.
Then it interprets the information it
receives.
Finally is makes the body respond to this
information.
The nervous system has 3 major functions.
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The nervous system receives signals:
called stimulus.
(this can be from inside or outside your
body)
When our nervous system reacts to
this stimulus it is called a: response.
This is how an organism interacts
with the environment.
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Consider what happens when you hear a
phone ring.
Nerves from your ear send a message to
your brain.
Your brain interprets this information as
the sound of a phone ringing.
Then your brain sends a message to your
arm muscles.
The muscles then contract, and you reach
out to lift the phone.
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Sports require an instant response to a
multitude of stimuli.
Name some examples of a sports
stimuli and the response:
Neurons: Your Body’s Relay Team
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Impulses travel throughout the nervous
system, but it does this via a sort of “relay
team” process.
Neurons make up that team.
Neurons: Your Body’s Relay Team
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A neuron, or nerve cell, is a basic unit
of the nervous system
which is made up of a cell body, and
branching dendrites that carry
electrical impulses to the cell body.
Neurons: Your Body’s Relay Team
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The cell body which is the largest part,
directs the action of the cell.
The axon then carries these messages
away from the cells body.
Axons end in a network of tiny branches.
When the impulses reach the end of the
axon, they come to a small space, a
synapse.
Neurons: Your Body’s Relay Team
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A neuron carries information from one
location to another.
Sensory neurons pick up information from
the environment.
Motor neurons carry information to
muscles or glands, causing them to act.
Interneurons, also called associate
neurons, carry information between 2 other
neurons.
Demonstration: 4 students & a note.
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Each student creates a stimulus (a
signal) to get the next student’s attention
(such as tapping the shoulder).
The students pass the note from one
person to the next.
The note is a nerve impulse, the signal
(shoulder tapping) is a stimulus, and
taking the note is the response.
A typical
neuron
is shown
in the
picture.
A typical neuron is shown in the picture.
A typical neuron
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The cell body contains the nucleus and most
of the cytoplasm.
Many long threadlike dendrites branch from
the cell body.
A long, thin fiber called an axon also extends
from the call body.
The axon is often coated with myelin, a white,
fatty material.
A typical neuron
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Axons are sometimes called nerve fibers.
These fibers occur in bundles called nerves.
The dendrites receive stimulation from the
environment or from the body.
If this stimulation is strong enough, a nerve
impulse, or message, is generated in the
axon.
A typical neuron
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The impulse travels along the axon. From the
end of the axon, a signal passes to a muscle, a
gland, or the dendrites of another neuron.
A synapse is the junction of an axon and the
structure with which it communicates.
The axon does not actually touch the muscle,
gland, or dendrites. There is a space of about
.00002 mm between the axon and the next
structure.
Demonstration: (Dominoes)
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Compare the movement through the
domino pattern to the transmission of a
nerve impulse:
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It is when these neurons are grouped
together that they form what we call:
nerves.
Nerve impulses are either heading for
the brain or leaving it.
8-2: The Parts of Your Nervous System
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Neurons make up the nervous system.
The nervous system is divided into 2
parts.
The central nervous system includes
the brain and the spinal cord.
The peripheral nervous system contains
all the nerves that lie outside the central
nervous system.
The Nervous System’s 2 Parts
The Central Nervous system
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Both the brain and the
spinal cord are
covered by 3
protective
membranes known as
the meninges.
The space between
the 2 inner meninges is
filled with
cerebrospinal fluid.
The Central Nervous system
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This fluid is produced in cavities within the
brain.
From there the fluid drains into blood
vessels in the brain.
Cerebrospinal fluid cushions the brain
and spinal cord against shock.
It also removes waste materials from the
brain.
The Central Nervous system
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The nervous tissue of the brain and spinal
cord lies under the meninges,
The outer portion of the brain tissue is
gray.
Beneath the gray layer,the brain is white.
In contrast, the spinal cord appears white
on the outside and gray on the inside.
The Brain: Operator of the Nervous System
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The processing of the stimuli that your
body receives every second of every day
is done by the central nervous system.
The central nervous system is made up of
the brain and the spinal cord.
The Brain: Operator of the Nervous System
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The brain, protected by your cranium or skull, is
divided up into 3 parts which are:
1.The cerebrum: which is the largest part of
the brain.
The brain of the human contains about 12
billion neurons.
Of the 12 billion, about 9 billion are contained
in the cerebrum.
It carries out the functions such as memory,
thought and speech.
The cerebrum:
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It receives nerve impulses from your skin, eyes,
ears, nose, and tongue,
and changes them into touch, sight, sound,
smell & taste.
It also sends out signals that control many
muscles.
This is where the senses are processed.
2.The cerebellum:
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This part processes the messages of an
activity,
sends messages to the cerebrum in what order
and how much force is needed for the muscles
to carryout needed actions,
and also helps you maintain balance.
It helps with the voluntary activities such as
muscle & skeletal movement.
The cerebellum helps maintain the balance of
your body.
3. The Brain stem (medulla oblongata):
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All nerve impulses to and from the brain
pass through the brain stem.
It is the part of the brain that connects with
the spinal cord.
It is also responsible for involuntary
activities such as control over digestion,
heartbeat, breathing, etc.
Involuntary body activities are usually those
that are crucial for survival.
(other parts for consideration)
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The thalamus lies beneath the cerebrum
and is a sensory relay station.
It receives impulses from most sensory
neurons entering the brain.
The thalamus also screens stimuli.
It prevents sensory overload.
(other parts for consideration)
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The hypothalamus lies beneath the thalamus.
It controls important sensations involved in
maintaining homeostasis, such as hunger
and thirst.
Temperature, water balance, and blood
pressure are also controlled by the
hypothalamus .
In addition, it also regulates the release of many
hormones.
4. The spinal cord.
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It runs the length of the backbone and is
protected by vertebrae and discs made of
cartilage.
It basically extends the brain stem down
the back.
Is acts as the connections between the
brain and the parts of the body.
Brain Diagrams
Brain Diagrams
Activity:
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The side of the brain that is dominant
can affect how people approach problem
solving.
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In partners: 1 person: writes a short
paragraph about their favorite sport.
The other person is to observe how the
person writes .
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Activity:
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How did they hold the pencil. __________
Where is the pencil in relationship to the paper. ____
Is the pencil straight ahead with the hand held under
the line: ___________
or is the pencil curved around with the point facing
toward the writer and the hand above the line of
writing? _______________________
Conclusions: Right brained or left brained?______
What does this mean to this person?
Is it accurate?________________________
Activity:
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One hemisphere of the brain is dominant over
the other.
The left hemisphere of the brain is usually
dominant.
Left-hemisphere dominance causes a person
to be right-handed.
In most people, an area in the left
hemisphere controls speech.
The left side of the brain is also specialized
for mathematics and logic.
Activity:
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The right side is usually specialized for art
and music.
The side of the brain that is dominant can
affect how people approach problem solving.
Studies have shown that usually the left side
of the brain solves complicated problems step
by step.
The right side of the brain is intuitive, tending
to see the whole picture rather than the
individual pieces.
Activity:
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Is the pencil straight ahead with the hand
held under the line, if so, that person has a
dominant left brain.
Is the pencil curved around with the point
facing toward the writer and the hand
above the line of writing?
That person has a dominant right brain.