1) A simple nervous system
A) must include chemical senses, mechanoreception, and
vision.
B) includes a minimum of 12 effector neurons.
C) has information flow in only one direction: toward an
integrating center.
D) has information flow in only one direction: away from
an integrating center.
E) includes sensory information, an integrating center,
and effectors.
Answer: E
2) Most of the neurons in the human brain are
A) sensory neurons.
B) motor neurons.
C) interneurons.
D) auditory neurons.
E) peripheral neurons.
Answer: C
3) The nucleus and most of the organelles in a neuron are
located in the
A) dendritic region.
B) axon hillock.
C) axon.
D) cell body.
E) axon terminals.
Answer: D
4) In certain large animals, this type of neuron can
extend beyond 1 meter in length.
A) glial cell in the brain
B) a sensory neuron
C) an interneuron
D) a glial cell at a ganglion
E) a neuron that controls eye movements
Answer: B
5) The somatic nervous system can alter the activities of
its targets, the skeletal muscle fibers, because
A) it is electrically coupled by gap junctions to the
muscles.
B) its signals bind to receptor proteins on the muscles.
C) its signals reach the muscles via the blood.
D) its light pulses activate contraction in the muscles.
E) it is connected to the internal neural network of the
muscles.
Answer: B
6) The point of connection between two communicating
neurons is called
A) the axon hillock.
B) the dendrite.
C) the synapse.
D) the cell body.
E) the glia.
Answer: C
7) In a simple synapse, neurotransmitter chemicals are
released by
A) the dendritic membrane.
B) the presynaptic membrane.
C) axon hillocks.
D) cell bodies.
E) ducts on the smooth endoplasmic reticulum.
Answer: B
8) In a simple synapse, neurotransmitter chemicals are
received by
A) the dendritic membrane.
B) the presynaptic membrane.
C) axon hillocks.
D) cell bodies.
E) ducts on the smooth endoplasmic reticulum.
Answer: A
9) In the communication between a motor neuron and a
skeletal muscle,
A) the motor neuron is considered the presynaptic cell
and the skeletal muscle is the postsynaptic cell.
B) the motor neuron is considered the postsynaptic cell
and the skeletal muscle is the presynaptic cell.
C) action potentials are possible on the motor neuron but
not the skeletal muscle.
D) action potentials are possible on the skeletal muscle
but not the motor neuron.
E) the motor neuron fires action potentials but the
skeletal muscle is not electrochemically excitable.
Answer: A
10) For a neuron with an initial membrane potential at
-70 mV, an increase in the movement of potassium ions out of that neuron's
cytoplasm would result in
A) the depolarization of the neuron.
B) the hyperpolarization of the neuron.
C) the replacement of potassium ions with sodium ions.
D) the replacement of potassium ions with calcium ions.
E) the neuron switching on its sodium-potassium pump to
restore the initial conditions.
Answer: B
11) 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
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.
Answer: B
12) The operation of the sodium-potassium
"pump" moves
A) sodium and potassium ions into the cell.
B) sodium and potassium ions out of the cell.
C) sodium ions into the cell and potassium ions out of
the cell.
D) sodium ions out of the cell and potassium ions into
the cell.
E) sodium and potassium ions into the mitochondria.
Answer: D
13) A cation that is more abundant as a solute in the
cytosol of a neuron than it is in the interstitial fluid outside the neuron is
A) HCO₃-.
B) Cl-.
C) Ca++.
D) Na+.
E) K+.
Answer: E
14) The membrane potential that exactly offsets an ion's
concentration gradient is called the
A) graded potential.
B) threshold potential.
C) equilibrium potential.
D) action potential.
E) inhibitory postsynaptic potential.
Answer: C
15) ATP hydrolysis directly powers the movement of
A) K+ out of cells.
B) Na+ out of cells.
C) Na+ into cells.
D) Ca++ into cells.
E) Cl- into cells.
Answer: B
16) Two fundamental concepts about the ion channels of a
"resting" neuron are that the channels
A) are always open, but the concentration gradients of
ions frequently change.
B) are always closed, but ions move closer to the
channels during excitation.
C) open and close depending on stimuli, and are specific
as to which ion can traverse them.
D) open and close depending on chemical messengers, and
are nonspecific as to which ion can traverse them.
E) open in response to stimuli, and then close
simultaneously, in unison.
Answer: C
17) Opening all of the sodium channels, with all other
ion channels closedwhich is an admittedly artificial
settingon an otherwise typical neuron should move its
membrane potential to
A) -90 mV.
B) -70 mV.
C) 0 mV.
D) +30 mV.
E) +62 mV.
Answer: E
18) A graded hyperpolarization of a membrane can be
induced by
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+.
Answer: E
19) Self-propagation and refractory periods are typical
of
A) action potentials.
B) graded hyperpolarizations.
C) excitatory postsynaptic potentials.
D) threshold potentials.
E) resting potentials.
Answer: A
20) The "selectivity" of a particular ion
channel refers to its
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.
Answer: E
21) A "resting" motor neuron is expected to
A) release lots of acetylcholine.
B) have high permeability to sodium ions.
C) be equally permeable to sodium and potassium ions.
D) exhibit a resting potential that is more negative than
the "threshold" potential.
E) have a higher concentration of sodium ions on the
inside of the cell than on the outside.
Answer: D
22) The "threshold" potential of a membrane
A) is the point of separation from a living to a dead
neuron.
B) is the lowest frequency of action potentials a neuron
can produce.
C) is the minimum hyperpolarization needed to prevent the
occurrence of action potentials.
D) is the minimum depolarization needed to operate the
voltage-gated sodium and potassium channels.
E) is the peak amount of depolarization seen in an action
potential.
Answer: D
23) Action potentials move along axons
A) more slowly in axons of large than in 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 non-myelinated
axons.
E) by reversing the concentration gradients for sodium
and potassium ions.
Answer: D
24) A toxin that binds specifically to voltage-gated
sodium channels in axons would be expected to
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.
Answer: B
25) After the depolarization phase of an action
potential, the resting potential is restored by
A) the opening of sodium activation gates.
B) the opening of voltage-gated potassium channels and
the closing of sodium channels.
C) a decrease in the membrane's permeability to potassium
and chloride ions.
D) a brief inhibition of the sodium-potassium pump.
E) the opening of more voltage-gated sodium channels.
Answer: B
26) The "undershoot" phase of
after-hyperpolarization is due to
A) slow opening of voltage-gated sodium channels.
B) sustained opening of voltage-gated potassium channels.
C) rapid opening of voltage-gated calcium channels.
D) slow restorative actions of the sodium-potassium
ATPase.
E) ions that move away from their open ion channels.
Answer: B
27) 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
A) hyperexcitable.
B) refractory.
C) fully depolarized.
D) above threshold.
E) at the equilibrium potential.
Answer: B
28) An action potential can start in the middle of an
axon and proceed in both opposite directions when
A) the neuron is an inhibitory neuron and operating
normally.
B) only the middle section of the axon has been
artificially stimulated by an electrode.
C) the dendritic region fires an action potential.
D) it is in its typical refractory state.
E) its membrane potential is above the threshold.
Answer: B
29) The primary means by which a neuron can communicate
to a second neuron is by
A) the frequency of its action potentials.
B) the peak of the depolarization phase of an action
potential.
C) the peak of the undershoot/hyperpolarization of an
action potential.
D) varying how much neurotransmitter it releases for a
given action potential.
E) remaining in the depolarization phase of the action
potential for an extended interval.
Answer: A
30) In the sequence of permeability changes for a
complete action potential, the first of these events that occurs is
A) the activation of the sodium-potassium
"pump."
B) the inhibition of the sodium-potassium
"pump."
C) the opening of voltage-gated sodium channels.
D) the closing of voltage-gated potassium channels.
E) the opening of voltage-gated potassium channels.
Answer: C
31) Saltatory conduction is a term applied to
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) 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.
Answer: E
32) The surface on a neuron that discharges the contents
of synaptic vesicles is the
A) dendrite.
B) axon hillock.
C) node of Ranvier.
D) postsynaptic membrane.
E) presynaptic membrane.
Answer: E
33) Neurotransmitters are released from axon terminals
via
A) osmosis.
B) active transport.
C) diffusion.
D) transcytosis.
E) exocytosis.
Answer: E
34) The fastest possible conduction velocity of action
potentials is observed in
A) thin, non-myelinated neurons.
B) thin, myelinated neurons.
C) thick, non-myelinated neurons.
D) thick, myelinated neurons.
Answer: D
35) Neural transmission across a mammalian synaptic gap
is accomplished by
A) the movement of sodium and potassium ions from the
presynaptic neuron into the postsynaptic neuron.
B) impulses traveling as electrical currents across the
gap.
C) impulses causing the release of a chemical signal and
its diffusion across the gap.
D) impulses ricocheting back and forth across the gap.
E) the movement of calcium ions from the presynaptic into
the postsynaptic neuron.
Answer: C
36) One possible disadvantage to a nerve net is that it
might conduct impulses in two directions from the point of the stimulus. Most
of the synapses in vertebrates conduct information in only one direction
A) as a result of the nodes of Ranvier.
B) as a result of voltage-gated sodium channels found
only in the vertebrate system.
C) because vertebrate nerve cells have dendrites.
D) because only the postsynaptic cells can bind and
respond to neurotransmitters.
E) because the sodium-potassium pump moves ions in one
direction.
Answer: D
37) The release of acetylcholine from the terminal of a
motor neuron is most directly linked to
A) the entry of potassium into the axon terminal.
B) the exit of potassium from the axon terminal.
C) the entry of sodium into the axon terminal.
D) the exit of sodium from the axon terminal.
E) the entry of calcium into the axon terminal.
Answer: E
38) 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) a voltage-gated sodium channel.
B) a voltage-gated potassium channel.
C) a ligand-gated sodium channel.
D) a second-messenger-gated sodium channel.
E) a chemical that inhibits action potentials.
Answer: C
39) An inhibitory postsynaptic potential (IPSP) occurs in
a membrane made more permeable to
A) potassium ions.
B) sodium ions.
C) calcium ions.
D) ATP.
E) all neurotransmitter molecules.
Answer: A
40) 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 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?
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
Answer: C
41) The activity of acetylcholine in a synapse is
terminated by
A) its active transport across the presynaptic membrane.
B) its diffusion across the presynaptic membrane.
C) its active transport across the postsynaptic membrane.
D) its diffusion across the postsynaptic membrane.
E) its degradation by a hydrolytic enzyme on the
postsynaptic membrane.
Answer: E
42) Adjacent neurons with direct (non-neurotransmitter)
action potential transfer are said to have electrical synapses, based on the
presence of
A) tight junctions at their point of contact.
B) gap junctions at their point of contact.
C) leaky junctions at their point of contact.
D) anchoring junctions at their point of contact.
E) desmosomes at their point of contact.
Answer: B
43) Ionotropic receptors are found at synapses operated
via
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.
Answer: A
44) An example of ligand-gated ion channels is
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.
Answer: B
45) An example of the action of metabotropic receptors is
when
A) voltage-gated ion channels open.
B) voltage-gated ion channels close.
C) acetylcholine-gated sodium channels open.
D) cAMP-linked ion channels open.
E) the undershoot/after-hyperpolarization occurs.
Answer: C
46) Neurotransmitters categorized as inhibitory are
expected to
A) act independently of their receptor proteins.
B) close potassium channels.
C) open sodium channels.
D) close chloride channels.
E) hyperpolarize the membrane.
Answer: E
47) When several EPSPs arrive at the axon hillock from
different dendritic locations, depolarizing the postsynaptic cell to threshold
for an action potential, this is an example of
A) temporal summation.
B) spatial summation.
C) tetanus.
D) the refractory state.
E) an action potential with an abnormally high peak of
depolarization.
Answer: B
48) When several IPSPs arrive at the axon hillock rapidly
in sequence from a single dendritic location, hyperpolarizing the postsynaptic
cell more and more and thus preventing an action potential, this is an example
of
A) temporal summation.
B) spatial summation.
C) tetanus.
D) the refractory state.
E) an action potential with an abnormally high peak of
depolarization.
Answer: A
49) 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
A) -72 mV.
B) -71 mV.
C) -70 mV.
D) -69 mV.
E) -68 mV.
Answer: A
50) Receptors for neurotransmitters are of primary
functional importance in assuring one-way synaptic transmission because they
are mostly found on the
A) axonal membrane.
B) axon hillock.
C) dendritic membrane.
D) mitochondrial membrane.
E) presynaptic membrane.
Answer: C
51) Functionally, which cellular location is the neuron's
"decision-making site" as to whether or not an action potential will
be initiated?
A) axonal membranes
B) axon hillocks
C) dendritic membranes
D) mitochondrial membranes
E) presynaptic membranes
Answer: B
52) Neurotransmitters affect postsynaptic cells by
A) initiating signal transduction pathways in the cells.
B) causing molecular changes in the cells.
C) affecting ion-channel proteins.
D) altering the permeability of the cells.
E) All of these options are correct.
Answer: E
53) The primary neurotransmitter from the parasympathetic
system that influences its autonomic targets is
A) acetylcholine.
B) adenosine.
C) norepinephrine.
D) adrenaline.
E) dopamine.
Answer: A
54) The major inhibitory neurotransmitter of the human
brain is
A) acetylcholine.
B) epinephrine.
C) glutamate.
D) nitric oxide.
E) GABA.
Answer: E
55) The major excitatory neurotransmitter of the human
brain is
A) acetylcholine.
B) epinephrine.
C) glutamate.
D) nitric oxide.
E) GABA.
Answer: C
56) A neuropeptide that might function as a natural
analgesic is
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.
Answer: C
57) An amino acid that operates at inhibitory synapses in
the brain is
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.
Answer: E
58) The botulinum toxin reduces the synaptic release of
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.
Answer: A
59) The heart rate decreases in response to the arrival
of
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.
Answer: A
60) A chemical that affects neuronal function but is not
stored in presynaptic vesicles is
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.
Answer: D
61) The membrane potential is closest to the equilibrium
potential for potassium at label
A) A.
B) B.
C) C.
D) D.
E) E.
Answer: D
62) The membrane's permeability to sodium ions is at its
maximum at label
A) A.
B) B.
C) C.
D) D.
E) E.
Answer: B
63) The minimum graded depolarization needed to operate
the voltage-gated sodium and potassium channels is indicated by the label
A) A.
B) B.
C) C.
D) D.
E) E.
Answer: A
64) 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
A) A.
B) B.
C) C.
D) D.
E) E.
Answer: C
65) The neuronal membrane is at its resting potential at
label
A) A.
B) B.
C) C.
D) D.
E) E.
Answer: E
66) Action potentials are normally carried in only one
direction: from the axon hillock toward the axon terminals. If you
experimentally depolarize the middle of the axon to threshold, using an
electronic probe, then
A) no action potential will be initiated.
B) an action potential will be initiated and proceed only
in the normal direction toward the axon terminal.
C) an action potential will be initiated and proceed only
back toward the axon hillock.
D) two action potentials will be initiated, one going
toward the axon terminal and one going back toward the hillock.
E) an action potential will be initiated, but it will die
out before it reaches the axon terminal.
Answer: D
67) Assume that excessive consumption of ethanol
increases the influx of negative chloride ions into "common sense"
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
A) increased membrane depolarization of "common
sense" neurons.
B) decreased membrane depolarization of "common
sense" neurons.
C) more action potentials in your "common
sense" neurons.
D) more EPSPs in your "common sense" neurons.
E) fewer IPSPs in your "common sense" neurons.
Answer: B
68) What happens when a resting neuron's membrane
depolarizes?
A) There is a net diffusion of Na+ out of the cell.
B) The equilibrium potential for K+ (EK) becomes more
positive.
C) The neuron's membrane voltage becomes more positive.
D) The neuron is less likely to generate an action
potential.
E) The cell's inside is more negative than the outside.
Answer: C
69) A common feature of action potentials is that they
A) cause the membrane to hyperpolarize and then
depolarize.
B) can undergo temporal and spatial summation.
C) are triggered by a depolarization that reaches the
threshold.
D) move at the same speed along all axons.
E) require the diffusion of Na+ and K+ through
ligand-gated channels to propagate.
Answer: C
70) Where are neurotransmitter receptors located?
A) the nuclear membrane
B) the nodes of Ranvier
C) the postsynaptic membrane
D) synaptic vesicle membranes
E) the myelin sheath
Answer: C
71) Temporal summation always involves
A) both inhibitory and excitatory inputs.
B) synapses at more than one site.
C) inputs that are not simultaneous.
D) electrical synapses.
E) multiple inputs at a single synapse.
Answer: E
72) Why are action potentials usually conducted in 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.
Answer: B
73) Which of the following is a direct result of
depolarizing the presynaptic membrane of an axon terminal?
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.
Answer: A
