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What are the basic structures of the neuron?
- Cell body
- Axon
- Dendrite
- Myelin sheaths
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Where can cell bodies of neurons be found?
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What function does the cell body fufill in the neuron?
Controls metabolism
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Besides the normal organelles, what two organelles do cell bodies have?
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What are neurofibrils?
- microtubules - move material
- (neurotransmitter, from cell body to end of axon)
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Describe the structure of dendrites.
- Highly branched
- Very numerous
- Relatively short
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What is the function of dendrites?
receive and transmit impulses toward cell body
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How many axons are connected to a cell body?
One
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Where do axons connect to on a cell body?
Axon hillock
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Describe the structure of an axon.
- Very in length
- May have branches
- At end, many short terminal branches may occur, each ending in synaptic knobs or bulbs that containsecretory vesicles filled with neurotransmitter.
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What is the function of an axon?
transmit nerve impulses away from cell body to another nerve cell, or to an effector cell.
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When do cell bodies and dendrites contain myelin sheaths?
Never
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What are the two types of axons and where can they be found?
- Myelinated - white matter
- Unmyelinated - gray matter
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What forms myelin sheaths in the PNS?
Schwann cells
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The outter layer of the myelin sheaths in the PNS is called what?
Neurolemma
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What gives the white appearence of myelin in the PNS?
The high lipid content.
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What are the nodes of Ranvier and what are their functions?
- Area between schwann cells that lack myelin.
- These act as conductive segments that allow nerve impulses to travel.
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Oligodendrocytes extend long processes that form _____ in the CNS.
myelin
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cell bodies and cytoplasm remain in spaces between neurons in the CNS, which means that there are no _____.
Neruolemma
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Nodes of Ranveir occur in what?
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Because of the absence of _____ in the CNS, it is unlikely that neurons will regenerate after injury.
Neurolemma
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Myelination development is completed when?
adolescence
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