Question 1

Neural transmission across a mammalian synapse is accomplished by

Accepted Answer

A)  the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. 
B)  impulses traveling as electrical currents across the synapse. 
C)  impulses causing the release of a chemical signal and its diffusion across the synapse. 
D)  impulses ricocheting back and forth across the synapse. 
E)  the movement of calcium ions from the presynaptic into the postsynaptic neuron. 
A)  the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. 
B)  impulses traveling as electrical currents across the synapse. 
C)  impulses causing the release of a chemical signal and its diffusion across the synapse. 
D)  impulses ricocheting back and forth across the synapse. 
E)  the movement of calcium ions from the presynaptic into the postsynaptic neuron.

Question 2

The following steps refer to various stages in transmission at a chemical synapse. 1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.
2) Calcium ions rush into the neuron's cytoplasm.
3) An action potential depolarizes the membrane of the axon terminal.
4) The ligand-gated ion channels open.
5) The synaptic vesicles release neurotransmitter into the synaptic cleft.
Which sequence of events is correct?

Accepted Answer

A)  1 → 2 → 3 → 4 → 5 
B)  2 → 3 → 5 → 4 → 1 
C)  3 → 2 → 5 → 1 → 4 
D)  4 → 3 → 1 → 2 → 5 
E)  5 → 1 → 2 → 4 → 3 
A)  1 → 2 → 3 → 4 → 5 
B)  2 → 3 → 5 → 4 → 1 
C)  3 → 2 → 5 → 1 → 4 
D)  4 → 3 → 1 → 2 → 5 
E)  5 → 1 → 2 → 4 → 3

Question 3

A graded hyperpolarization of a membrane can be induced by

Accepted Answer

A)  increasing its membrane's permeability to Na+. 
B)  decreasing its membrane's permeability to H+. 
C)  decreasing its membrane's permeability to Cl-. 
D)  increasing its membrane's permeability to Ca++. 
E)  increasing its membrane's permeability to K+. 
A)  increasing its membrane's permeability to Na+. 
B)  decreasing its membrane's permeability to H+. 
C)  decreasing its membrane's permeability to Cl-. 
D)  increasing its membrane's permeability to Ca++. 
E)  increasing its membrane's permeability to K+.

Question 4

Immediately after an action potential passes along an axon, it is not possible to generate a second action potential; thus, we state that the membrane is briefly

Accepted Answer

A)  hyperexcitable. 
B)  refractory. 
C)  fully depolarized. 
D)  above threshold. 
E)  at the equilibrium potential. 
A)  hyperexcitable. 
B)  refractory. 
C)  fully depolarized. 
D)  above threshold. 
E)  at the equilibrium potential.

Question 5

For the following questions, refer to the graph of an action potential in Figure 37.1.
   Figure 37.1
-The period in which voltage-gated potassium channels are open and hyperpolarization has yet to occur is at label

Accepted Answer

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

Question 6

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 7

Saltatory conduction is a term applied to

Accepted Answer

A)  conduction of impulses across electrical synapses. 
B)  an action potential that skips the axon hillock in moving from the dendritic region to the axon terminal. 
C)  the rapid movement of an action potential reverberating back and forth along a neuron. 
D)  jumping from one neuron to an adjacent neuron. 
E)  jumping from one node of Ranvier to the next in a myelinated neuron. 
A)  conduction of impulses across electrical synapses. 
B)  an action potential that skips the axon hillock in moving from the dendritic region to the axon terminal. 
C)  the rapid movement of an action potential reverberating back and forth along a neuron. 
D)  jumping from one neuron to an adjacent neuron. 
E)  jumping from one node of Ranvier to the next in a myelinated neuron.

Question 8

The "selectivity" of a particular ion channel refers to its

Accepted Answer

A)  permitting passage by positive but not negative ions. 
B)  permitting passage by negative but not positive ions. 
C)  ability to change its size depending on the ion needing transport. 
D)  binding with only one type of neurotransmitter. 
E)  permitting passage only to a specific ion. 
A)  permitting passage by positive but not negative ions. 
B)  permitting passage by negative but not positive ions. 
C)  ability to change its size depending on the ion needing transport. 
D)  binding with only one type of neurotransmitter. 
E)  permitting passage only to a specific ion.

Question 9

A neuropeptide that might function as a natural analgesic is

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 10

Why are action potentials usually conducted in one direction?

Accepted Answer

A)  The nodes of Ranvier conduct potentials in one direction. 
B)  The brief refractory period prevents reopening of voltage gated Na+ channels. 
C)  The axon hillock has a higher membrane potential than the terminals of the axon. 
D)  Ions can flow along the axon in only one direction. 
E)  Voltage-gated channels for both Na+ and K+ open in only one direction. 
A)  The nodes of Ranvier conduct potentials in one direction. 
B)  The brief refractory period prevents reopening of voltage gated Na+ channels. 
C)  The axon hillock has a higher membrane potential than the terminals of the axon. 
D)  Ions can flow along the axon in only one direction. 
E)  Voltage-gated channels for both Na+ and K+ open in only one direction.

Question 11

The activity of acetylcholine in a synapse is terminated by its

Accepted Answer

A)  active transport across the presynaptic membrane. 
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 on the postsynaptic membrane. 
A)  active transport across the presynaptic membrane. 
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 on the postsynaptic membrane.

Question 12

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 membranes 
B)  axon hillocks 
C)  dendritic membranes 
D)  mitochondrial membranes 
E)  presynaptic membranes 
A)  axonal membranes 
B)  axon hillocks 
C)  dendritic membranes 
D)  mitochondrial membranes 
E)  presynaptic membranes

Question 13

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 14

A toxin that binds specifically to 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 15

An example of ligand-gated ion channels is

Accepted Answer

A)  the spreading of action potentials in the heart. 
B)  acetylcholine receptors at the neuromuscular junction. 
C)  cAMP-dependent protein kinases. 
D)  action potentials on the axon. 
E)  graded hyperpolarization. 
A)  the spreading of action potentials in the heart. 
B)  acetylcholine receptors at the neuromuscular junction. 
C)  cAMP-dependent protein kinases. 
D)  action potentials on the axon. 
E)  graded hyperpolarization.

Question 16

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

Accepted Answer

A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
E)  An EPSP or IPSP is generated in the postsynaptic cell. 
A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
E)  An EPSP or IPSP is generated in the postsynaptic cell.

Question 17

For the following questions, refer to the graph of an action potential in Figure 37.1.
   Figure 37.1
-The cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened, at label

Accepted Answer

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

Question 18

Assume that excessive consumption of ethanol increases the influx of negative chloride ions into "commonsense" neurons whose action potentials are needed for you to act appropriately and not harm yourself or others. Thus, any resulting poor decisions associated with ethanol ingestion are likely due to

Accepted Answer

A)  increased membrane depolarization of "commonsense" neurons. 
B)  increased membrane hyperpolarization of "commonsense" neurons. 
C)  more action potentials in your "commonsense" neurons. 
D)  more EPSPs in your "commonsense" neurons. 
E)  fewer IPSPs in your "commonsense" neurons. 
A)  increased membrane depolarization of "commonsense" neurons. 
B)  increased membrane hyperpolarization of "commonsense" neurons. 
C)  more action potentials in your "commonsense" neurons. 
D)  more EPSPs in your "commonsense" neurons. 
E)  fewer IPSPs in your "commonsense" neurons.

Question 19

Ionotropic receptors are found at synapses operated via

Accepted Answer

A)  ligand-gated ion channels. 
B)  second-messenger-gated ion channels. 
C)  electrical synapses. 
D)  inhibitory, but not excitatory, synapses. 
E)  excitatory, but not inhibitory, synapses. 
A)  ligand-gated ion channels. 
B)  second-messenger-gated ion channels. 
C)  electrical synapses. 
D)  inhibitory, but not excitatory, synapses. 
E)  excitatory, but not inhibitory, synapses.

Question 20

Motor neurons alter skeletal muscle activities by releasing neurotransmitter because

Accepted Answer

A)  they are electrically coupled by gap junctions to the muscles. 
B)  their signals bind to receptor proteins on the muscles. 
C)  their signals reach the muscles via the blood. 
D)  their light pulses activate contraction in the muscles. 
E)  they are connected to the internal neural network of the muscles. 
A)  they are electrically coupled by gap junctions to the muscles. 
B)  their signals bind to receptor proteins on the muscles. 
C)  their signals reach the muscles via the blood. 
D)  their light pulses activate contraction in the muscles. 
E)  they are connected to the internal neural network of the muscles.

Exam 37: Neurons, Synapses, and Signaling

Neural transmission across a mammalian synapse is accomplished by

A graded hyperpolarization of a membrane can be induced by

Immediately after an action potential passes along an axon, it is not possible to generate a second action potential; thus, we state that the membrane is briefly

For the following questions, refer to the graph of an action potential in Figure 37.1. Figure 37.1 -The period in which voltage-gated potassium channels are open and hyperpolarization has yet to occur is at label

Action potentials move along axons

Saltatory conduction is a term applied to

The "selectivity" of a particular ion channel refers to its

A neuropeptide that might function as a natural analgesic is

Why are action potentials usually conducted in one direction?

The activity of acetylcholine in a synapse is terminated by its

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

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

A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to

An example of ligand-gated ion channels is

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

For the following questions, refer to the graph of an action potential in Figure 37.1. Figure 37.1 -The cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened, at label

Ionotropic receptors are found at synapses operated via

Motor neurons alter skeletal muscle activities by releasing neurotransmitter because

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