Question 1

For the following questions, refer to the graph of an action potential.
 
-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

Accepted Answer

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.F) C) and D)
G) None of the above

Question 2

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

Accepted Answer

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.F) D) and E)
G) A) and D)

Question 3

In certain large animals, this type of neuron can extend beyond 1 meter in length.

Accepted Answer

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 movementsF) A) and C)
G) B) and D)

Question 4

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.F) A) and B)
G) A) and C)

Question 5

The activity of acetylcholine in a synapse is terminated by

Accepted Answer

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.F) A) and D)
G) A) and B)

Question 6

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

Accepted Answer

A)   HCO₃⁻.
B)   Cl⁻.
C)   Ca⁺⁺.
D)   Na⁺.
E)   K⁺.F) A) and E)
G) None of the above

Question 7

The operation of the sodium-potassium "pump" moves

Accepted Answer

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.F) A) and B)
G) A) and C)

Question 8

The primary means by which a neuron can communicate to a second neuron is by

Accepted Answer

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.F) None of the above
G) B) and D)

Question 9

In a simple synapse, neurotransmitter chemicals are received by

Accepted Answer

A)   the dendritic membrane.
B)   the presynaptic membrane.
C)   axon hillocks.
D)   cell bodies.
E)   ducts on the smooth endoplasmic reticulum.F) D) and E)
G) B) and D)

Question 10

For the following questions, refer to the graph of an action potential.
 
-The neuronal membrane is at its resting potential at label

Accepted Answer

A)   A.
B)   B.
C)   C.
D)   D.
E)   E.F) None of the above
G) All of the above

Question 11

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

Accepted Answer

A)   temporal summation.
B)   spatial summation.
C)   tetanus.
D)   the refractory state.
E)   an action potential with an abnormally high peak of depolarization.F) B) and D)
G) A) and D)

Question 12

A neuropeptide that might function as a natural analgesic is

Accepted Answer

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

Question 13

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.F) A) and B)
G) A) and C)

Question 14

In the sequence of permeability changes for a complete action potential, the first of these events that occurs is

Accepted Answer

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.F) A) and E)
G) C) and E)

Question 15

The surface on a neuron that discharges the contents of synaptic vesicles is the

Accepted Answer

A)   dendrite.
B)   axon hillock.
C)   node of Ranvier.
D)   postsynaptic membrane.
E)   presynaptic membrane.F) B) and D)
G) C) and D)

Question 16

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.F) D) and E)
G) B) and C)

Question 17

Two fundamental concepts about the ion channels of a "resting" neuron are that the channels

Accepted Answer

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.F) A) and D)
G) A) and E)

Question 18

An amino acid that operates at inhibitory synapses in the brain is

Accepted Answer

A)   acetylcholine.
B)   epinephrine.
C)   endorphin.
D)   nitric oxide.
E)   GABA.F) All of the above
G) A) and D)

Question 19

An action potential can start in the middle of an axon and proceed in both opposite directions when

Accepted Answer

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.F) All of the above
G) A) and B)

Question 20

An example of the action of metabotropic receptors is when

Accepted Answer

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.F) A) and B)
G) B) and C)

Exam 48: Neurons, Synapses, and Signaling

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

Correct AnswerverifiedShow Answer

An action potential can start in the middle of an axon and proceed in both opposite directions when

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Two fundamental concepts about the ion channels of a "resting" neuron are that the channels

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

An amino acid that operates at inhibitory synapses in the brain is

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The surface on a neuron that discharges the contents of synaptic vesicles is the

Correct AnswerverifiedShow Answer

A neuropeptide that might function as a natural analgesic is

Correct AnswerverifiedShow Answer

The operation of the sodium-potassium "pump" moves

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

For the following questions, refer to the graph of an action potential. -The neuronal membrane is at its resting potential at label

Correct AnswerverifiedShow Answer

In certain large animals, this type of neuron can extend beyond 1 meter in length.

Correct AnswerverifiedShow Answer

In the sequence of permeability changes for a complete action potential, the first of these events that occurs is

Correct AnswerverifiedShow Answer

The primary means by which a neuron can communicate to a second neuron is by

Correct AnswerverifiedShow Answer

For the following questions, refer to the graph of an action potential. -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

Correct AnswerverifiedShow Answer

In a simple synapse, neurotransmitter chemicals are received by

Correct AnswerverifiedShow Answer

The activity of acetylcholine in a synapse is terminated by

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

An example of the action of metabotropic receptors is when

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified