CHAPTER 39—INFORMATION FLOW AND THE NEURON
MULTIPLE CHOICE
1. Nervous system cells that send and receive electrical signals, for example, when a dog is anticipating
the throwing of a Frisbee, are called
a.
receptors.
b.
neurons.
c.
sensors.
d.
glial cells.
e.
signal cells.
2. ____ assist and nourish cells that transmit electrical signals.
a.
Receptors
b.
Neurons
c.
Effector cells
d.
Glial cells
e.
Signal cells
3. The component of a neural signaling pathway in which messages are sorted and interpreted is called
a.
a response.
b.
integration.
c.
transmission.
d.
reception.
e.
action.
4. In humans and some primates, which category of neurons is composed of the greatest number of cells?
a.
efferent neurons
b.
afferent neurons
c.
interneurons
d.
motor neurons
e.
sensory neurons
5. Which of the following components of a neural signaling pathway are correctly arranged from
beginning to end?
a.
integration, transmission, reception, response, transmission
b.
transmission, response, reception, transmission, integration
c.
response, reception, transmission, integration, transmission
d.
reception, transmission, integration, transmission, response
e.
transmission, integration, transmission, reception, response
6. ____ conduct(s) electrical signals away from the cell body of a neuron.
a.
An axon terminal
b.
An axon
c.
An axon hillock
d.
The nucleus
e.
Dendrites
7. Which cells are part of the vertebrate peripheral nervous system?
a.
afferent neurons
b.
motor neurons
c.
efferent neurons
d.
afferent and efferent neurons
e.
afferent, motor and efferent neurons
8. Which cells are located in the brain and spinal cord of vertebrates?
a.
interneurons
b.
motor neurons
c.
afferent neurons
d.
efferent neurons
e.
afferent and efferent neurons
9. What type of neuron directly stimulates a muscle or gland?
a.
afferent neuron
b.
efferent neuron
c.
interneuron
d.
afferent and efferent neurons
e.
afferent neurons and interneurons
10. Which glial cell(s) is/are only found in the peripheral nervous system?
a.
Schwann cells
b.
oligodendrocytes
c.
astrocytes
d.
Schwann cells and oligodendrocytes
e.
Schwann cells and astrocytes
11. What category(s) of organic macromolecule allow(s) myelinated sheaths to act as electrical insulators?
a.
proteins
b.
carbohydrates
c.
lipids
d.
nucleic acids
e.
proteins and nucleic acids
Use the figure above for the following question(s).
12. In this chemical synapse, which structure represents the synaptic cleft?
a.
A
b.
B
c.
C
d.
D
e.
E
13. In this chemical synapse, which structure represents the axon terminal of a presynaptic cell?
a.
A
b.
B
c.
C
d.
D
e.
E
14. In this chemical synapse, which structure represents the vesicle releasing neurotransmitter molecules?
a.
A
b.
B
c.
C
d.
D
e.
E
15. In this chemical synapse, which structure represents the receptors that bind neurotransmitter
molecules?
a.
A
b.
B
c.
C
d.
D
e.
E
16. Otto Loewi demonstrated that neurons transmit signals across synapses
a.
by electrical signals.
b.
by Vagusstoff.
c.
by acetylcholine.
d.
by chemical signals.
e.
by proteins
17. For a neuron, the outside of the plasma membrane has a higher concentration of ____ than the inside
of the plasma membrane.
a.
Na+
b.
K+
c.
Ca2+
d.
anions
e.
ATP
18. The neuron resting membrane potential is established due to all of the following EXCEPT
a.
the activity of Na+/K+ active transport pumps.
b.
the presence of impermeable intracellular anions.
c.
the buildup of Na+ outside the plasma membrane and K+ inside the plasma membrane.
d.
the distribution of ions inside and outside an axon.
e.
the threshold potential.
19. When measuring membrane potential, the tip of a microelectrode is inserted into a(n)
a.
axon.
b.
node of Ranvier.
c.
Schwann cell.
d.
dendrite.
e.
glial cell.
20. The typical resting potential of an isolated neuron is
a.
−60 mV.
b.
−70 mV.
c.
−80 mV.
d.
−90 mV.
e.
−100 mV.
21. An abrupt and transient change in membrane potential is called a(n)
a.
electrical potential.
b.
refractory potential.
c.
threshold potential.
d.
resting potential.
e.
action potential.
22. When a neuron membrane potential becomes less negative it becomes
a.
depolarized.
b.
hyperpolarized.
c.
repolarized.
d.
damaged.
e.
activated above the threshold potential.
23. The minimum level of depolarization required to initiate an action potential in an excitable cell is
called the
a.
electrical potential.
b.
refractory potential.
c.
membrane potential.
d.
resting potential.
e.
threshold potential.
24. When a neuron membrane potential goes below its resting value it becomes
a.
depolarized.
b.
hyperpolarized.
c.
repolarized.
d.
damaged.
e.
re-stimulated.
25. The refractory period of a neuron plasma membrane is important because
a.
it establishes the resting potential.
b.
it initiates an action potential.
c.
it ensures that the threshold potential will be reached.
d.
it ensures that an impulse will travel in a one-way direction.
e.
in resets the threshold potential.
26. During an action potential, the membrane potential can reach as high as
a.
+30 mV.
b.
+40 mV.
c.
+50 mV.
d.
+60 mV.
e.
+70 mV.
27. When threshold potential is reached, which of the following occurs?
a.
The activation gates of Na+ channels open.
b.
The inactivation gates of Na+ channels open.
c.
The activation gates of K+ channels open.
d.
The inactivation gates of Na+ channels open.
e.
Na+/K+ active transport pumps are activated.
28. When threshold potential is reached, which of the following occurs?
a.
The activation gates of Na+ channels close.
b.
The inactivation gates of Na+ channels close.
c.
The activation gates of K+ channels close.
d.
The inactivation gates of Na+ channels close.
e.
Na+/K+ active transport pumps are activated.
29. If the K+ channels of an excitable plasma membrane were blocked by the action of a drug, which of the
following would be disrupted?
a.
repolarization
b.
depolarization
c.
hyperpolarization
d.
repolarization and depolarization
e.
repolarization and hyperpolarization
30. Depolarization of the neuron plasma membrane occurs due to
a.
the diffusion of K+ into the cell.
b.
the diffusion of K+ out of the cell.
c.
the diffusion of Na+ into the cell.
d.
the diffusion of Na+ out of the cell.
e.
closed gated channels.
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Use the figure above for the following question(s).
31. At what point in this action potential diagram are Na+ inactivation gates opening and K+ activation
gates closing?
a.
A
b.
B
c.
C
d.
D
e.
E
32. At what point in this action potential diagram are many Na+ activation gates open and K+ activation
gates closed?
a.
A
b.
B
c.
C
d.
D
e.
E
33. At what point in this action potential diagram does the onset of Na+ channel inactivation stop the
inward flow of Na+?
a.
A
b.
B
c.
C
d.
D
e.
E
34. An action potential is propagated down an unmyelinated neuron plasma membrane because
a.
the action potential stimulates voltage-gated Na+ channels adjacent to it.
b.
the action potential stimulates voltage-gated Ca2+ channels adjacent to it.
c.
the action potential stimulates voltage-gated K+ channels adjacent to it.
d.
the action potential stimulates voltage-gated Na+ and Ca2+ channels adjacent to it.
e.
the action potential stimulates voltage-gated k+ and Ca2+ channels adjacent to it.
35. Action potentials are propagated in a one-way direction down a neuron plasma membrane because
a.
the action potential is of insufficient intensity to stimulate the voltage-gated ion channels
behind it.
b.
the adjacent channels upstream from the action potential are ligand-gated.
c.
the adjacent channels upstream from the action potential are in their refractory period.
d.
voltage-gated ion channels are suppressed.
e.
the adjacent channels upstream from the action potential are at their threshold potential.
36. The magnitude of an action potential ____ as it is propagated down an excitable membrane. This is
due to the ____.
a.
increases; all-or-nothing principle
b.
remains constant; all-or-nothing principle
c.
increases; threshold principle
d.
remains constant; threshold principle
e.
increases; refractory principle
37. The intensity of an electrical impulse is reflected in the
a.
frequency of action potentials.
b.
magnitude of action potentials.
c.
duration of action potentials.
d.
intensity of action potentials.
e.
the frequency and duration of action potentials.
38. A reasonable estimation of the duration of an action potential is
a.
approximately five microseconds.
b.
approximately five milliseconds.
c.
approximately five centiseconds.
d.
approximately five seconds.
e.
approximately five nanoseconds.
39. For which axon might you expect action potential propagation to be the fastest?
a.
a myelinated axon with a small diameter
b.
an unmyelinated axon with a small diameter
c.
a myelinated axon with a large diameter
d.
an unmyelinated axon with a large diameter
e.
axon myelination and diameter do not affect action potential propagation rate
40. The spaces between adjacent Schwann cells are called
a.
nodes of Ranvier.
b.
axon terminals.
c.
dendrites.
d.
intercalated discs.
e.
active gaps.
41. The disease multiple sclerosis causes myelin degeneration in vertebrate nervous systems. Knowing
this, what symptoms/effects might you NOT expect in a person with multiple sclerosis?
a.
slowed action potential transmission
b.
tissue numbness
c.
muscular weakness
d.
faulty coordination of movements
e.
memory loss
42. Place the following events in the order in which they occur for chemical synapse transmission.
(1)
Ca2+ enters axon terminal.
(2)
Ligand-gated ion channels open in postsynaptic membrane.
(3)
Neurotransmitter binds to postsynaptic receptor.
(4)
Action potential reaches axon terminal of presynaptic neuron.
(5)
Neurotransmitter released by exocytosis.
a.
4, 1, 5, 3, 2
b.
4, 3, 1, 5, 2
c.
4, 5, 1, 3, 2
d.
4, 1, 3, 5, 2
e.
4, 5, 2, 3, 1
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43. Chemical synapses are distinctive for all of the following EXCEPT
a.
they require the use of ligand-gated ion channels.
b.
they require the use of voltage-gated ion channels.
c.
they may utilize direct neurotransmitters.
d.
they require the use of vesicles.
e.
they require proteins.
44. Vesicles containing neurotransmitters are released into the synaptic cleft when ____ levels rise within
the axon terminal.
a.
Na+
b.
K+
c.
Cl−
d.
Ca2+
e.
H+
45. What removes Ca2+ from the inside of an axon terminal of a chemical synapse after an electrical
impulse has passed?
a.
ion channels
b.
active transport pumps
c.
passive carrier proteins
d.
exocytosis
e.
simple diffusion through the plasma membrane
46. The binding of a neurotransmitter to ligand-gated K+ channels will cause ____ in the postsynaptic
membrane.
a.
depolarization
b.
hyperpolarization
c.
repolarization
d.
apolarization
e.
depolarization and repolarization
47. The binding of a neurotransmitter to ligand-gated Cl− channels will cause ____ in the postsynaptic
membrane.
a.
depolarization
b.
hyperpolarization
c.
repolarization
d.
apolarization
e.
depolarization and repolarization
48. The binding of a neurotransmitter to ligand-gated Na+ channels will cause ____ in the postsynaptic
membrane.
a.
depolarization
b.
hyperpolarization
c.
repolarization
d.
apolarization
e.
depolarization and repolarization
49. In vertebrates, the neurotransmitter acetylcholine
a.
can act as a direct neurotransmitter between neurons and muscle cells.
b.
can make it more difficult for some postsynaptic membranes to reach threshold.
c.
can be released into circulation and act as a hormone.
d.
can act as a pain reducer and initiate euphoria.
e.
a and b only
50. Neuropeptide neurotransmitters
a.
can act as a direct neurotransmitter between neurons and muscle cells.
b.
can act as a postsynaptic membrane inhibitors.
c.
directly open K+ channels to inhibit neurons.
d.
can act as pain reducers and initiate euphoria.
e.
directly inhibit euphoria.
51. Jean-Luc Eiselé and his coworkers used ______ receptors in their research on neurotransmitter
receptor function.
a.
African clawed frog
b.
toad
c.
artificial
d.
dog
e.
human
52. The neurotransmitter receptor research of Jean-Luc Eiselé and his coworkers shows that
a.
neurotransmitters are dependent on the activity of Na+.
b.
neurotransmitters are dependent on the activity of K+.
c.
neurotransmitters are dependent on the activity of Cl−.
d.
a receptor binding to neurotransmitters functions independently from conducting ions.
e.
neurotransmitters are dependent on the activity of Ca+.
53. A graded, subthreshold change in the postsynaptic membrane potential that moves it toward threshold
is called a(n)
a.
IPSP.
b.
hyperpolarization.
c.
EPSP.
d.
depolarization.
e.
repolarization.
54. Assume a neuron receives EPSPs and IPSPs from several adjacent neurons. How might that neuron’s
threshold potential be reached, causing it to produce its own action potential?
a.
if IPSPs outnumber EPSPs
b.
temporal summation
c.
spatial summation
d.
temporal and spatial summation
e.
if IPSPs equal EPSPs
55. At what neuron location does summation occur?
a.
dendrites
b.
cell body
c.
axon hillock
d.
Schwann cells
e.
axon terminals
56. What neuron location has the greatest density of voltage-gated Na+ channels, resulting in the lowest
threshold potential along a neuron?
a.
dendrites
b.
cell body
c.
axon hillock
d.
axon
e.
axon terminals
57. Approximately how many neurons are in the human brain?
a.
1,000
b.
10,000
c.
100,000
d.
100,000,000
e.
100,000,000,000
58. The transmission of information from one neuron to another has been found to occur by all of the
following mechanisms EXCEPT
a.
neurotransmitters released from vesicles.
b.
components of a membrane can act as neurotransmitters.
c.
electrical connections.
d.
chemical signals transmitted through electrical connections.
e.
a gas that diffuses through a cell membrane.
Select the Exception
59. Which of the following is NOT a component of neural signaling mechanisms?
a.
reception
b.
action
c.
transmission
d.
response
e.
integration
60. Which of the following neurons is NOT typically located in the peripheral nervous system?
a.
afferent neurons
b.
sensory neurons
c.
efferent neurons
d.
interneurons
e.
motor neurons
61. Which of the following structures are NOT used by chemical synapses during signal transmission?
a.
gap junctions
b.
ligand-gated receptors
c.
Ca2+
d.
vesicles
e.
neurotransmitters
62. Which of the following does NOT involve K+?
a.
repolarization
b.
hyperpolarization
c.
depolarization
d.
resting membrane potential
e.
dampening of neural activity
63. Which of the following does NOT represent a change in membrane potential?
a.
EPSP
b.
threshold potential
c.
depolarization
d.
repolarization
e.
IPSP
64. Which of the following structures is NOT actively involved with saltatory conduction?
a.
oligodendrocytes
b.
myelin
c.
Na+/K+ pumps
d.
voltage-gated Na+ channels
e.
nodes of Ranvier
65. Which of the following is NOT a possible result of EPSP & IPSP activity?
a.
An unusually strong action potential forms.
b.
No summation.
c.
EPSPs and IPSPs cancel each other out.
d.
Temporal summation.
e.
Spatial summation.
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MATCHING
Match each of the following terms with its correct description.
a.
An electrical potential difference across a plasma membrane
b.
A subthreshold change in membrane potential toward the threshold potential of a neuron
c.
The membrane potential of an excitable membrane when it is not being stimulated
d.
A subthreshold change in membrane potential away from the threshold potential of a
neuron
e.
An abrupt, transient change in membrane potential, consisting of membrane depolarization
followed by repolarization
f.
Minimum membrane potential required to form an action potential
g.
Any subthreshold change in membrane potential whose effects are additive
66. graded potential
67. action potential
68. membrane potential
69. resting potential
70. IPSP
71. EPSP
72. threshold potential
Choice
For each of the following situations, choose the most appropriate term.
a.
depolarization
b.
repolarization
c.
hyperpolarization
73. an IPSP is an example of this
74. occurs due to the diffusion of Na+
75. an EPSP is an example of this
76. causes a neuron membrane potential to become more negative, allowing it to approach its resting
potential
77. occurs in a postsynaptic membrane when ligand-gated Na+ channels open
78. the phase of an action potential when the membrane potential becomes more positive
79. begins when Na+ channel inactivation gates close and K+ activation gates open
80. describes the change in resting membrane potential that causes it to approach threshold potential
81. occurs when a membrane potential becomes more negative than its resting membrane potential
82. occurs in a postsynaptic membrane when ligand-gated Cl− channels open
MODIFIED TRUE/FALSE
If the statement is true, answer “T“. If the statement is false, answer “F” and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
83. Afferent neurons carry electric impulses directly to muscles and glands.
84. Oligodendrocytes are responsible for myelinating central nervous system axons.
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85. Neurotransmitters are stored in vesicles located within axon terminals.
86. Depolarization occurs due to the diffusion of K+ across a neuron plasma membrane.
87. Saltatory conduction is the slowest form of action potential propagation.
88. Direct neurotransmitters bind to G-protein coupled receptors.
89. Action potentials never vary in magnitude along a particular excitable membrane.
90. Depending on the type of receptor to which it binds, the same neurotransmitter may repolarize or
hyperpolarize potentials in the postsynaptic cell.
91. The additive effect of one neuron sending many EPSPs to another neuron over a brief period of time is
called spatial summation.
92. EPSPs can form due to the diffusion of Na+ across a neuron plasma membrane.
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SHORT ANSWER
93. Explain how neuron action potential propagation rate can be increased.
94. Explain how the resting membrane potential and resting ion distributions are established in a neuron.
95. Valium is a drug that causes voltage-gated Cl− channels to open. What effects would this cause in a
postsynaptic membrane?
OBJ: Bloom’s Taxonomy: Knowledge | Bloom’s Taxonomy: Application
96. A toxin interferes with the opening of Na+ channels in the postsynaptic membrane so they open more
slowly when bound to a neurotransmitter. What effect would there be on action potential formation in
the postsynaptic membrane?
97. In terms of changes in membrane potential, compare and contrast action potentials and graded
potentials.