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CHAPTER 3: Cellular Organization of the Nervous System

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In the CNS, astrocytes:

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A. buffer Na+ in the CNS neuropil.

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B. promote axonal elongation.

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C. create the blood–brain barrier.

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D. form myelin around CNS axons.

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E. emit inhibitory axons to pain endings.

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C. create the blood–brain barrier.

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Concerning the generation and propagation of action potentials, which of the following is correct?

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A. Subthreshold excitatory stimuli do not summate; either they produce an action potential or they do not.

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B. Demyelination produces “bare” areas on axons and allows faster saltatory conduction.

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C. “Cable properties” of axons indicate that axons with a small cross-section area have less resistance to ion flow and therefore conduct action potentials faster than large axons.

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D. Myelinated axons conduct impulses rapidly because the myelin is contractile and squeezes the charged ions forward.

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E. If a stimulus exceeds the threshold of the action potential, a spike will be produced; if not, the cell will return to its resting membrane potential (all-or-none principle).

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E. If a stimulus exceeds the threshold of the action potential, a spike will be produced; if not, the cell will return to its resting membrane potential (all-or-none principle).

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Concerning protein synthesis and transportation in neurons, which of the following statements is correct?

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A. Membranes of the Golgi apparatus are studded with ribosomes.

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B. Kinesin is the most important transport molecule related to retrograde axon transport.

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C. Free ribosomes package newly formed proteins into vesicles.

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D. RNA polymerase converts ribosomal RNA into messenger RN.

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E. Translation is the process that ends with a new protein being formed.

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E. Translation is the process that ends with a new protein being formed.

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Comparing axons and dendrites:

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A. only axons contain microtubules.

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B. both can be sites of synapses.

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C. most dendrites are thinly myelinated.

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D. axons are the main input sites and dendrites the main output sites.

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E. both participate ...

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