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The Nervous Sysem
- Central Nervouis System
- .Brain and Spinal Cord
- Peripheral Nervous System
- .Nerve cells that send messages to the central nervous system
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Neurons
- Nerve Cells
- .Communicate with each other to send and receive messages from other parts of the body
- .Muscles and glands
- .We have 100 billion neurons mostly in the brain
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Neurons
Cell Body
Produces energy that fuels activity
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Neuron
Dendrites
Receives information from other neurons and passes messages through cell body
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Neurons
Axon
Carries messages away from cell body
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Neuron
Myelin
White fatty sunstance that insulates and protects axon
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Neuron
Myelin Sheath
Speeds transmission of messages
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Neuron
Axon terminals
Small fibers at the end of the axon that branch out
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Synapse
A junction between the axon terminals of one neuron and the dendrites of another neuron
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Sensory Neurons
Carry information received by the sense to the central nervous system
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Motor Neurons
Carry information from the central nervous system to the muscles and glands and influnce their functioning
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Neurotransmitters
Chemicals stores in sacs in the axon terminals
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Acetylcholine
A neurotransmitter that, among its functions, triggers muscle contractions
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Endorphins
- .Means "morphine within"
- .Natural, opiate-like neurotransmitters
- .Linked to pain control and to pleasure
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The Central Nervous System
- .Consists of neurons of the spinal cord and the brain
- .Spinal cord extend from the brain down the back
- .Spinal reflex:a simple, automatic response to something
- .Touching something hot on the stove
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Peripheral Nervous System
.Responsible for transmitting messages between the central nervous system and all parts of the body
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Two Main Divisions of the Peripheral Nervous System
- .Somatic: transmits sensory messages to the CNS
- .Activated by touch, pain, changes in temperature or body position
- .Autonomic (means involuntary): regulates body's vital functions such as heartbeat, breathing, digestion and blood pressure
- .Sympathetic: Prepares the body for action
- ."fight or flight" response: when the body decides what route to take in an uncertain situation
- .Parasympathetic: restores the body after action
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