A simple nervous system
A) must include chemical senses,
mechanoreception, and vision.
B) includes a minimum of 12
ganglia.
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) has information
flow both toward and away from an integrating center.
E
Most of the neurons in the human brain are
A) sensory
neurons.
B) motor neurons.
C) interneurons.
D) auditory
neurons.
E) olfactory neurons.
C
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.
D
In certain large animals, this type of neuron can extend beyond one
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.
B
) A nervous system can alter activities in its target cells in
muscles and glands because
A) they are electrically coupled by
gap junctions.
B) the target cells have receptor proteins for the
signals released by the nervous system.
C) the nervous system
releases signals into the blood to control the target cells.
D)
the target cells that become disconnected from the nervous system
rapidly die.
E) the target cells each have an internal neural
network connected to the nervous system
B
) In the communication link 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
A
For a neuron with an initial membrane potential at -70 mV, an
increase in the movement of
potassium ions out of that neuronʹs
cytoplasm would result in
A) depolarization of the
neuron.
B) 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.
B
Though the membrane of a ʺrestingʺ neuron is highly permeable to
potassium ions, its
membrane potential does not exactly match the
equilibrium potential for potassium
because the neuronal membrane
is
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.
B
The operation of the sodium-potassium ʺpumpʺ 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.
D
) The ʺselectivityʺ 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.
E
A ʺrestingʺ motor neuron is expected to
A) releases lots of
acetylcholine.
B) to have high permeability to sodium
ions.
C) to be equally permeable to sodium and potassium
ions.
D) exhibit a resting potential that is more negative than
the ʺthresholdʺ potential.
E) have a higher concentration of
sodium ions on the inside the cell than on the outside.
D
The ʺthresholdʺ potential of a membrane
A) is the point of
separation from a living from 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.
D
) 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 ʺpumpʺ 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
D
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.
B
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
activation gates.
C) a decrease in the
membraneʹs permeability to potassium and chloride ions.
D) a
brief inhibition of the sodium-potassium pump.
E) the opening of
more voltage-gated sodium channels.
B
The membrane potential is closest to the equilibrium potential for potassium at label
D
The membraneʹs permeability to sodium ions is at its maximum at label
B
The minimum graded depolarization needed to operate the voltage
-gated sodium and
potassium channels is indicated by the label
A
The cell is not hyperpolarized, but repolarization is in progress, as
the sodium channels are
closing or closed, and many potassium
channels have opened, at label
C
The neuronal membrane is at its resting potential at label
E
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
D
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 ʺpump.ʺ
B) the inhibition of
the sodium-potassium ʺpump.ʺ
C) the opening of voltage-gated
sodium channels.
D) the closing of voltage-gated potassium
channels.
E) the opening of voltage-gated potassium channels.
C
Saltatory conduction is a term applied to conduction of
impulses
A) 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.
E
) The surface on a neuron that discharges synaptic vesicles is
the
A) dendrite.
B) axon hillock.
C) node of
Ranvier.
D) postsynaptic membrane.
E) presynaptic membrane.
E
Neurotransmitters are released from axon terminals via
A)
osmosis.
B) active transport.
C) diffusion.
D)
transcytosis.
E) exocytosis.
E
Neural transmission across a mammalian synaptic gap is accomplished
by
A) the movement of sodium and potassium ions from the
presynaptic 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.
C
One disadvantage to a nerve net is that it can 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.
D
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
C
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.
A
The steps below 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 neuronʹs
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
C
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.
E
Assume that excessive consumption of ethanol increases the influx of
negative chloride ions
into ʺcommon senseʺ 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 ʺcommon senseʺ neurons.
B) decreased membrane
depolarization of ʺcommon senseʺ neurons.
C) more action
potentials in your ʺcommon senseʺ neurons.
D) more EPSPs in your
ʺcommon senseʺ neurons.
E) fewer IPSPs in your ʺcommon senseʺ neurons.
B
) Neurotransmitters categorized as inhibitory would 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.
E
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.
B
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.
A
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 initial
membrane potential is -70 mV,
the net effect of the simultaneous arrival of 6 IPSPs and 2
EPSPs
would be to move the membrane potential to
A) -72 mV.
B) -71
mV.
C) -70 mV.
D) -69 mV.
E) -68 mV
A
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.
C
Functionally, this cellular location is the neuronʹs ʺdecision-making
siteʺ 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
B
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) Choices A, B, C, and D
are all correct.
E
) The primary neurotransmitter from the parasympathetic system that
influences its
autonomic targets is
A)
acetylcholine.
B) adenosine.
C) norepinephrine.
D)
adrenaline.
E) dopamine.
A
1) The major inhibitory neurotransmitter of the human brain
is
A) acetylcholine.
B) epinephrine.
C)
endorphin.
D) nitric oxide.
E) GABA.
E
A neuropeptide that might function as a natural analgesic is
A)
acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric
oxide.
E) GABA.
C
An amino acid that operates at inhibitory synapses in the
brain
A) acetylcholine
B) epinephrine
C)
endorphin
D) nitric oxide
E) GABA
E
The botulinum toxin reduces the synaptic release of
A)
acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric
oxide.
E) GABA.
A
The heart naturally slows when responding to
A)
acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric
oxide.
E) GABA
A
This neuro-active compound is not stored in presynaptic
vesicles:
A) acetylcholine
B) epinephrine
C)
endorphin
D) nitric oxide
E) GABA
D
What happens when a neuronʹs 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 neuronʹs
membrane voltage becomes more positive.
D) The neuron becomes
less likely to generate an action potential.
E) The inside of the
cell becomes more negative relative to the outside.
C
Why are action potentials usually conducted in only one direction
along an axon?
A) The nodes of Ranvier can conduct potentials in
only 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.
B
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) result from the diffusion of Na+ and K+
through ligand-gated channels
C
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`
A
Where are neurotransmitter receptors located?
A) on the nuclear
membrane
B) at nodes of Ranvier
C) on the postsynaptic
membrane
D) on the membranes of synaptic vesicles
E) in the
myelin sheath
C
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)
myelinated axons.
E