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What is a nerve?
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A bundle of hundreds to thousands of axons, C.T and blood vessels that lies outside the braind and spinal cord.
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Spinal Cord
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Contains 31 pairs of spinal nerves
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Ganglia
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"Swelling or knot"
Small masses of nervous tissue, mostly body cells of neurons, outside the brain and spinal cord. Associated with cranial, spinal nerves. |
`Enteris plexuses
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The extensive networks of neurons in walls of organs and GI tract.
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Sensory receptors
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Dendrites of sensory neurons, or separate, specialized cells that monitor chainges in internal, external environments.
Photoreceptors in retina of eye. |
Functions of nervous system
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Carries out complex tasks: sensing smells, producing speech, providing signals that control body movments, etc.
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Sensory function
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Sensory receptors that detect internal stimuli:
Inc. in blood acidity External: raindrop landing on arm. |
Sensory (Afferent) neurons
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Carry information from lower level to higher level in spinal cord and brain.
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Integrative function
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Intergrates (processes) sensory information by analyzing and storing some of it and making decisions.
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Interneurons
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Many neurons that participate in integration.
The axons extend only for a short distance, contact nearby neurons in brain, spinal cord or ganglion. |
Motor function
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Responding to integration decisions.
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Effectors
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Cells and organs contacted by motor neurons in cranial and spinal nerves.
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Central nervous system (CNS)
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Brain and spinal cord: Thoughts, memories and emotions.
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Peripheral nervous system (PNS)
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All nerves, except brain and spinal cord. Include cranial, spinal nerves, their branches, ganglia and sensory receptors.
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Axillary nerve
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Supplies the deltoid and teres minor muscles.
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