18. Action potentials: a. are invariant, always reaching the same amplitude. b.

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Question

18. Action potentials:

a. are invariant, always reaching the same amplitude.

b. are graded with the number of ligand-gated ionotropic channels that open.

c. have a threshold.

d. require the opening of voltage-gated Na+ channels for initiation.

e. all except b are correct

20. You would expect to find the output regions of neurons that release the neurotransmitter GABA in:

a. muscle innervated by lower motor neurons.

b. spinal nerves.

c. gray matter of the CNS.

d. the spinothalamic tract.

e. dorsal columns of the spinal cord.

22. The resting membrane potential in neurons largely results from a gradient of ___ ions and open _____.

a. Na+, Na+ leak channels

b. impermeant anions, impermeant anion channels

c. K+, K+ leak channels

d. Cl, Cl leak channels

e. Na+, voltage-gated Na+ channels

18. (d) require the opening of voltage gated Na+ channel for initiation.

20.(e) dorsal column of spinal cord, GABA is neurotransmitter release in dorsal horn of spinal cord.

22. (e) Na+, voltage gated Na+ channels

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