1. Neurons are greatly outnumbered by _______________ cells, whichperform various supportive and protective roles in the nervous system.

2. The cell body of a neuron receives information from processescalled _______________ and transmits signals tothe next cell by way of a process called the _______________

3. The axon hillock and initial segment of a neuron constitute its , so namedbecause this is where action potentials are first generated.

4. Neurons that carry signals from the CNS to muscles and glands arecalled _______________ neurons.

5. Neurons contained entirely in the CNS are called .

6. The myelin sheath is formed by _______________ in the CNS and by _______________ in the PNS.

7. The periodic gaps in a myelin sheath are called .

8. Neurotransmitters are released by the exocytosis of organellescalled _______________ .

9. _______________ is any shift in the membrane voltage of a neuron toward 0 mV.

10. A small positive voltage change caused by a neurotransmitter iscalled a/an _______________ .

11. For a neuron to fire, several of the voltage changes in question10 must occur and add up to a minimum voltage called the _______________ .

12. The rising phase of an action potential is produced by theinflux of _______________ .

13. In a myelinated neuron, _______________ ion gates areconcentrated in the trigger zone and nodes of Ranvier and are scarce elsewhere on thecell.

14. Name any two catecholamines.

15. _______________ is aprocess in which one neuron can suppress the release of a neurotransmitter by anotherneuron.

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