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CHAPTER 3: Cellular Organization of the Nervous System

In the CNS, astrocytes:

A. buffer Na+ in the CNS neuropil.

B. promote axonal elongation.

C. create the blood–brain barrier.

D. form myelin around CNS axons.

E. emit inhibitory axons to pain endings.

C. create the blood–brain barrier.

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

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

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

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.

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

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).

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).

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

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

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

C. Free ribosomes package newly formed proteins into vesicles.

D. RNA polymerase converts ribosomal RNA into messenger RN.

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

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

Comparing axons and dendrites:

A. only axons contain microtubules.

B. both can be sites of synapses.

C. most dendrites are thinly myelinated.

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

E. both participate ...

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