Download The Nervous System

The Nervous System
The glue that keeps all the parts and systems
working together.
Coordinating the Body Systems
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Keeps all systems up and running, so it can
never rest.
Homeostasis
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Occurs when all systems are working correctly
Your body is in balance
Five More Jobs
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Responsible for maintaining your
consciousness
Monitors alertness and awareness of
surroundings
Interprets senses
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Sensory organs: ears, eyes, nose, skin, tongue
Reactions to senses
Your learning and memory
Two parts of the nervous system
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Central Nervous System
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Brain and spinal cord
Peripheral Nervous System
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Nerves throughout your body
Central Nervous System
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Brain and spinal cord
Your brain is protected by your skull
Your spinal cord is protected by the vertebrae
in your spine
Peripheral Nervous System
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The rest of your nervous system – spread
throughout your body
Peripheral means “outside”
Nerves including:
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12 pairs of cranial nerves coming from your head
31 pairs of spinal nerves coming from your
backbone
Autonomic Nervous System
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Controls your involuntary muscles
Such as the cardiac and smooth muscles
Are nerves really made of steel?
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Made of individual nerve cells called neurons
What do neurons look like?
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Cell body with branches, or arms, coming out of
the body.
One type of the arms is called a dendrite
The other type of arm is called an axon
Dendrite
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Receives messages
Carries messages to the center of the cell
called the nucleus
Axon
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Carry messages away from the center of the
cell towards other cells.
Messages travel one way: from a dendrite
through the cell body to an axon.
Three different kinds of neuron cells
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Sensory neuron
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Interphase neuron
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Gathers information and sends it to your brain or
to your spinal cord
Receives information from a sensory neuron
Motor neuron
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Carries information to muscles or glands in the
body
How the neurons work together…
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Imagine you are riding a bicycle and see a red stop sign.
Your sensory neurons in your eyes gather the
information. The sensory neurons carry information to
your brain where the information is passed onto
interphase neurons. Then the interphase neurons pass
the information to the motor neurons. The motor
neurons travel to your leg muscles and tell those
muscles to help you stop the bicycle.
Sensory Neuron  Interphase Neuron  Motor Neuron
How is the information transferred?
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Synapse
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When an axon from one nerve is carrying
information to the dendrite of another nerve
It uses special chemicals to send the information
The information is passed through synapse, yet
the cells never actually come in direct contact.
Brain – Part 1
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Cerebrum
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Largest part of the brain
Many folds increasing the total surface area
Controls all conscious body movement
Interprets information gathered by your senses
Divided into left and right hemispheres
Left side controls the ability to speak, use math and think
logically
Right side controls your musical abilities, your artistic
skills and your emotions.
Brain – Part 2
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Cerebellum
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Controls all the voluntary muscles in your body
Makes sure your movements are smooth and
coordinated
Controls your balance and muscle tone
Brain – Part 3
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Brain stem
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Connects your brain to your spinal cord
Automatic body processes are controlled by the
brain stem
Controls your heartbeat, your breathing and your
blood pressure
Reflexes
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Caused by stimulus
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Anything that causes a response
Reflex actions help keep us healthy and safe