Question 1

GABA is

Accepted Answer

A) a chemical that affects neuronal function but is not stored in presynaptic vesicles. 
B) an amino acid that operates at inhibitory synapses in the brain. 
C) a neuropeptide that might function as a natural analgesic. 
D) the major inhibitory neurotransmitter of the human brain. 
A) a chemical that affects neuronal function but is not stored in presynaptic vesicles. 
B) an amino acid that operates at inhibitory synapses in the brain. 
C) a neuropeptide that might function as a natural analgesic. 
D) the major inhibitory neurotransmitter of the human brain.

Question 2

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y.A likely explanation is that

Accepted Answer

A) the threshold value in the postsynaptic membrane is different for cell X and cell Y. 
B) the axon of cell X is myelinated,but that of cell Y is not. 
C) only cell Y produces an enzyme that terminates the activity of the neurotransmitter. 
D) cells X and Y express different receptor molecules for this particular neurotransmitter. 
A) the threshold value in the postsynaptic membrane is different for cell X and cell Y. 
B) the axon of cell X is myelinated,but that of cell Y is not. 
C) only cell Y produces an enzyme that terminates the activity of the neurotransmitter. 
D) cells X and Y express different receptor molecules for this particular neurotransmitter.

Question 3

In a simple synapse,neurotransmitter chemicals are released by

Accepted Answer

A) the dendritic membrane. 
B) the presynaptic membrane. 
C) axon hillocks. 
D) cell bodies. 
A) the dendritic membrane. 
B) the presynaptic membrane. 
C) axon hillocks. 
D) cell bodies.

Question 4

The activity of acetylcholine in a synapse is terminated by its

Accepted Answer

A) active transport out of the synaptic cleft. 
B) diffusion across the presynaptic membrane. 
C) active transport across the postsynaptic membrane. 
D) diffusion across the postsynaptic membrane. 
E) degradation by a hydrolytic enzyme in the synaptic cleft. 
A) active transport out of the synaptic cleft. 
B) diffusion across the presynaptic membrane. 
C) active transport across the postsynaptic membrane. 
D) diffusion across the postsynaptic membrane. 
E) degradation by a hydrolytic enzyme in the synaptic cleft.

Question 5

A drug that specifically inhibits voltage-gated sodium channels in axons would be expected to

Accepted Answer

A) prevent the hyperpolarization phase of the action potential. 
B) prevent the depolarization phase of the action potential. 
C) prevent graded potentials. 
D) increase the release of neurotransmitter molecules. 
E) have most of its effects on the dendritic region of a neuron. 
A) prevent the hyperpolarization phase of the action potential. 
B) prevent the depolarization phase of the action potential. 
C) prevent graded potentials. 
D) increase the release of neurotransmitter molecules. 
E) have most of its effects on the dendritic region of a neuron.

Question 6

Assume that a single IPSP has a negative magnitude of -0.5 mV at the axon hillock and that a single EPSP has a positive magnitude of +0.5 mV.For a neuron with an initial membrane potential of -70 mV,the net effect of the simultaneous arrival of six IPSPs and two EPSPs would be to move the membrane potential to

Accepted Answer

A) -72 mV. 
B) -71 mV. 
C) -70 mV. 
D) -69 mV. 
E) -68 mV. 
A) -72 mV. 
B) -71 mV. 
C) -70 mV. 
D) -69 mV. 
E) -68 mV.

Question 7

Which of the following principles characterize gated ion channels in the neuronal membrane? Select all that apply.
I.Channels are always open.
II.Channels are always closed.
III.Channels open and close depending on stimuli.
IV.Channels are specific to which ions can traverse them.
V.Channels are nonspecific to which ions can traverse them.

Accepted Answer

A) I and V only 
B) II and IV only 
C) III and IV only 
D) II and V only 
E) III and V only 
A) I and V only 
B) II and IV only 
C) III and IV only 
D) II and V only 
E) III and V only

Question 8

Action potentials move along axons

Accepted Answer

A) more slowly in axons of large diameter as compared to those of small diameter. 
B) by the direct action of acetylcholine on the axonal membrane. 
C) by activating the sodium-potassium "pump" at each point along the axonal membrane. 
D) more rapidly in myelinated than in nonmyelinated axons. 
E) by reversing the concentration gradients for sodium and potassium ions. 
A) more slowly in axons of large diameter as compared to those of small diameter. 
B) by the direct action of acetylcholine on the axonal membrane. 
C) by activating the sodium-potassium "pump" at each point along the axonal membrane. 
D) more rapidly in myelinated than in nonmyelinated axons. 
E) by reversing the concentration gradients for sodium and potassium ions.

Question 9

Ionotropic receptors are found at synapses operated via

Accepted Answer

A) ligand-gated ion channels. 
B) metabotropic receptors. 
C) inhibitory,but not excitatory,synapses. 
D) excitatory,but not inhibitory,synapses. 
A) ligand-gated ion channels. 
B) metabotropic receptors. 
C) inhibitory,but not excitatory,synapses. 
D) excitatory,but not inhibitory,synapses.

Question 10

The observation that the acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of a

Accepted Answer

A) voltage-gated sodium channel. 
B) voltage-gated potassium channel. 
C) ligand-gated sodium channel. 
D) second-messenger-gated sodium channel. 
E) chemical that inhibits action potentials. 
A) voltage-gated sodium channel. 
B) voltage-gated potassium channel. 
C) ligand-gated sodium channel. 
D) second-messenger-gated sodium channel. 
E) chemical that inhibits action potentials.

Question 11

The membrane potential that exactly offsets an ion's concentration gradient is called the

Accepted Answer

A) graded potential. 
B) threshold potential. 
C) equilibrium potential. 
D) action potential. 
E) inhibitory postsynaptic potential. 
A) graded potential. 
B) threshold potential. 
C) equilibrium potential. 
D) action potential. 
E) inhibitory postsynaptic potential.

Question 12

The fastest possible conduction velocity of action potentials is observed in

Accepted Answer

A) thin,nonmyelinated axons. 
B) thin,myelinated axons. 
C) thick,nonmyelinated axons. 
D) thick,myelinated axons. 
A) thin,nonmyelinated axons. 
B) thin,myelinated axons. 
C) thick,nonmyelinated axons. 
D) thick,myelinated axons.

Question 13

________ occurs when several excitatory postsynaptic potentials (EPSPs)arrive at the axon hillock from different dendritic locations and then depolarize the postsynaptic cell to threshold for an action potential

Accepted Answer

A) Temporal summation 
B) Spatial summation 
C) A normal action potential 
A) Temporal summation 
B) Spatial summation 
C) A normal action potential

Question 14

Suppose you are a researcher examining the impacts of ion channels on resting membrane potential in typical neurons.By using a drug,you artificially open all sodium channels and keep all other ion channels closed.What value of the resting membrane potential should you observe?

Accepted Answer

A) -90 mV 
B) -70 mV 
C) 0 mV 
D) +30 mV 
E) +62 mV 
A) -90 mV 
B) -70 mV 
C) 0 mV 
D) +30 mV 
E) +62 mV

Question 15

The botulinum toxin inhibits the synaptic release of

Accepted Answer

A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA. 
A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA.

Question 16

Functionally,which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated?

Accepted Answer

A) axonal membrane 
B) axon hillock 
C) dendritic membrane 
A) axonal membrane 
B) axon hillock 
C) dendritic membrane

Question 17

Self-propagation and refractory periods are typical of

Accepted Answer

A) action potentials. 
B) graded hyperpolarizations. 
C) excitatory postsynaptic potentials. 
D) inhibitory postsynaptic potentials. 
E) resting potentials. 
A) action potentials. 
B) graded hyperpolarizations. 
C) excitatory postsynaptic potentials. 
D) inhibitory postsynaptic potentials. 
E) resting potentials.

Question 18

Neurotransmitters that hyperpolarize neuron membranes are categorized as

Accepted Answer

A) excitatory. 
B) inhibitory. 
C) neutral. 
A) excitatory. 
B) inhibitory. 
C) neutral.

Question 19

Figure 37.2
-Suppose you are studying a toxin from a new species of poisonous snake,and you find that neurons exposed to the toxin can initiate action potentials,but they cannot send electrical signals to other neurons.What structure in Figure 37.2 is the toxin targeting?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 20

Although the membrane of a "resting" neuron is highly permeable to potassium ions,its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also

Accepted Answer

A) fully permeable to sodium ions. 
B) slightly permeable to sodium ions. 
C) fully permeable to calcium ions. 
D) impermeable to sodium ions. 
E) highly permeable to chloride ions. 
A) fully permeable to sodium ions. 
B) slightly permeable to sodium ions. 
C) fully permeable to calcium ions. 
D) impermeable to sodium ions. 
E) highly permeable to chloride ions.

Exam 37: Neurons,synapses,and Signaling

GABA is

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y.A likely explanation is that

In a simple synapse,neurotransmitter chemicals are released by

The activity of acetylcholine in a synapse is terminated by its

A drug that specifically inhibits voltage-gated sodium channels in axons would be expected to

Action potentials move along axons

Ionotropic receptors are found at synapses operated via

The observation that the acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of a

The membrane potential that exactly offsets an ion's concentration gradient is called the

The fastest possible conduction velocity of action potentials is observed in

________ occurs when several excitatory postsynaptic potentials (EPSPs)arrive at the axon hillock from different dendritic locations and then depolarize the postsynaptic cell to threshold for an action potential

Suppose you are a researcher examining the impacts of ion channels on resting membrane potential in typical neurons.By using a drug,you artificially open all sodium channels and keep all other ion channels closed.What value of the resting membrane potential should you observe?

The botulinum toxin inhibits the synaptic release of

Functionally,which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated?

Self-propagation and refractory periods are typical of

Neurotransmitters that hyperpolarize neuron membranes are categorized as

Figure 37.2 -Suppose you are studying a toxin from a new species of poisonous snake,and you find that neurons exposed to the toxin can initiate action potentials,but they cannot send electrical signals to other neurons.What structure in Figure 37.2 is the toxin targeting?

Although the membrane of a "resting" neuron is highly permeable to potassium ions,its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also

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