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28 Cards in this Set
- Front
- Back
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What neuroglia is similar to an astrocyte in that is has slender cytoplasmic extensions, but has smaller cell bodies and fewer processes than astrocytes? |
Oligodedrocytes |
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What are the processes of oligodendrocytes generally in contact with? |
Exposed surfaces of neurons |
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What is the function of the oligodendrocytes processes ending at the neuron cell body? |
It has yet to be determined |
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What are many axons in the CNS completely sheathed in? |
Oligodendrocyte processes |
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What does the oligodendrocyte process insulate the CNS from? |
Contact with the extracellular fluid |
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During its maturation, what does the plasma membrane near the tip of each process of an oligodendrocyte expand to form? |
An enormous pad |
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When is the enormous pad at the tip of each process of an eligodendrocyte formed? |
During its maturation |
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What happens to the cytoplasm in this enormous pad? |
It becomes very thin |
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This enormous pad can also be called a flattened what? |
Pancake |
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When the flattened "pancake" somehow gets wrapped around the axolemma, what is formed? |
Concentric layers of plasma membrane |
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What is the membranous wrapping around the axolemma formed by flattened "pancake" called? |
Myelin |
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What does myelin serve as? |
An electrical insulation |
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What does myelin increase? |
The speed at which an action potential travels along the axon |
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What do oligodendrocytes cooperate to form along the length of an axon? |
Myelin sheath |
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What is an axon covered with a myelin sheath said to be? |
Myelinated |
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Each oligodendrocyte myelinates segments of several what? |
Axons |
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What are the fairly large areas of the axon that are wrapped in myelin called? |
Internodes |
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Typically, how long are internodes? |
1-2 MM |
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The small gaps of a few micrometers that separate adjacent internodes are called what? |
Nodes |
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What is another name for nodes? |
Nodes of Ranview |
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What part of the axon originates at the nodes? |
Collateral branches |
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Why do dissected myelinated axons appear glossy white. |
Primarily because of the lipids in the myelin |
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What are regions of the CNS dominated by myelinated axons known as? |
White matter |
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What are axons not completely covered by oligodendrocytes called? |
Unmyelinated |
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Unmyelinated axons are common where short axons and collaterals form what? |
A synapse with densely packed neuron cell bodies |
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What are the areas containing neuron cell bodies, dendrites, and unmyelinated axons with a dusky gray color called? |
Gray matter |
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Oligodendrocytes play an important role in structural organization by tying what together? |
Clusters of axons |
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How do oligodendrocytes improve the function of neurons? |
By wrapping axons within a myelin sheath |
