Chapter 22

Each of the following is a type of glial cells except

interneurons.

The axon branches of a typical neuron terminate at structures called

boutons.

Plasma membrane permeability of which of the following ions is most important in generating the resting membrane potential?

potassium ions

Generation of an action potential by a neuron may ultimately stimulate

All of the above may be stimulated by a signal.

Sodium channels are concentrated in the

axon hillock and nodes of Ranvier.

The maximum membrane potential that an ion gradient can produce is the

equilibrium potential.

The resting potential of a particular nerve cell is - 66 mV. Depolarization of the neuron membrane will shift the membrane potential to

+45 mV.

At which point in the graph do voltage-gated potassium channels open?

C

Based on the graph, the threshold voltage appears to be approximately

-40mV

Based on the graph, how soon could another action potential be easily initiated (at the end of the relative refractory period) after the first stimulus?

3 msec

Which point on the graph represents the threshold potential?

B

The parts of the graph indicated between points C and E represent

repolarization.

If the membrane represented in the graph was stimulated in the presence of a drug that specifically inhibits sodium channels, the membrane would

not depolarize

Each of the following contributes to the unidirectional propagation of nerve signals except

ion channels are oriented to transport ions only into the neuron.

Each of the following statements about action potentials is true except

action potentials are propagated along a dendrite.

Multiple sclerosis is a result of

demyelination of nerve cells.

The technique that can be used to record ion currents passing through individual channels is known as

patch-clamping

The phase at the end of an action potential when the membrane potential becomes more negative than it is at rest is the ________ phase.

hyperpolarizing

Each of the following is a voltage-gated Na⁺ channel property except

opens to a variable extent depending on how much the stimulus voltage exceeds the threshold voltage.

Each of the following is a correct relationship between action potential phase and channel status except

hyperpolarizing phase; Na⁺ channels open.

An example of a generally inhibitory neurotransmitter is

GABA.

The intracellular stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in

calcium ion levels

You have added a specific amount of excitatory neurotransmitter mixed with a 6× higher concentration of an inhibitory neurotransmitter to a synaptic cleft. You expect that the postsynaptic neuron will

show a net hyperpolarization as a result of neuronal integration

A drug that specifically inhibits voltage-gated calcium channels would most directly inhibit

presynaptic neurotransmitter release

Hyperpolarization of the postsynaptic nerve terminal

decreases the chance that an action potential will be initiated.