Question 1

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. 
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.

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. 
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.

Question 3

What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?

Accepted Answer

A) The action potential would be propagated nearly instantaneously to the synapse. 
B) There would be no action potential generated at the axon hillock. 
C) The signal would fade because it is not renewed by the opening of more sodium channels. 
D) The action potential would be slower than normal for that length of axon. 
E) The action potential would be more negative than normal. 
A) The action potential would be propagated nearly instantaneously to the synapse. 
B) There would be no action potential generated at the axon hillock. 
C) The signal would fade because it is not renewed by the opening of more sodium channels. 
D) The action potential would be slower than normal for that length of axon. 
E) The action potential would be more negative than normal.

Question 4

The "undershoot" phase of after-hyperpolarization is due to

Accepted Answer

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. 
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.

Question 5

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) 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) 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 6

The heart rate decreases in response to the arrival of

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 7

Which of the following will increase the speed of an action potential moving down an axon?
I.larger diameter axons.
II.lack of potassium ion channels.
III.myelinated axons.

Accepted Answer

A) only III 
B) only I and II 
C) only II and III 
D) only I and III 
E) I, II, and III 
A) only III 
B) only I and II 
C) only II and III 
D) only I and III 
E) I, II, and III

Question 8

In multiple sclerosis the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results.How does this disease manifest at the level of the action potential?
I.Action potentials move in the opposite direction on the axon.
II.Action potentials move more slowly along the axon.
III.No action potentials are transmitted.

Accepted Answer

A) only I 
B) only II 
C) only III 
D) only II and III 
E) I, II and III 
A) only I 
B) only II 
C) only III 
D) only II and III 
E) I, II and III

Question 9

Which is the correct order for processing and integrating sensory stimuli?

Accepted Answer

A) stimuli → sensory neuron → sensory nerve → CNS → PNS 
B) stimuli → sensory nerve → sensory neuron → PNS → CNS 
C) stimuli → sensory neuron → sensory nerve → PNS → CNS 
D) stimuli → sensory nerve → sensory neuron → CNS → PNS 
E) sensory nerve → stimuli → sensory neuron → PNS → CNS 
A) stimuli → sensory neuron → sensory nerve → CNS → PNS 
B) stimuli → sensory nerve → sensory neuron → PNS → CNS 
C) stimuli → sensory neuron → sensory nerve → PNS → CNS 
D) stimuli → sensory nerve → sensory neuron → CNS → PNS 
E) sensory nerve → stimuli → sensory neuron → PNS → CNS

Question 10

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. 
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.

Question 11

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 12

Neurotransmitters affect postsynaptic cells by

Accepted Answer

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. 
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.

Question 13

If you experimentally increase the concentration of Na⁺ outside a cell while maintaining other ion concentrations as they were,what would happen to the cell's membrane potential?

Accepted Answer

A) The membrane potential would decrease. 
B) The membrane potential would increase. 
C) The membrane potential would be unaffected. 
D) The membrane potential depends on the thermodynamic potential. 
E) The membrane potential depends on the concentration of K⁺ 
A) The membrane potential would decrease. 
B) The membrane potential would increase. 
C) The membrane potential would be unaffected. 
D) The membrane potential depends on the thermodynamic potential. 
E) The membrane potential depends on the concentration of K⁺

Question 14

Use the following information to answer the next few questions.
Over the course of a year,you notice that you are more frequently losing your balance,are unable to keep your train of thought,and occasionally have double vision.After visiting several specialists,you are diagnosed with multiple sclerosis (MS),the hardening and ultimate loss of the myelin sheath which insulates axons.
-The onset of these symptoms follows the loss of the myelin sheath,leading to

Accepted Answer

A) a loss in conduction speed of action potentials 
B) an increase in conduction speed of action potentials. 
C) consistent depolarization at the nodes of Ranvier. 
D) increased saltatory conduction. 
E) an increased diameter of the axon. 
A) a loss in conduction speed of action potentials 
B) an increase in conduction speed of action potentials. 
C) consistent depolarization at the nodes of Ranvier. 
D) increased saltatory conduction. 
E) an increased diameter of the axon.

Question 15

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 16

Which of the following ions is most likely to cross the plasma membrane of a resting neuron?

Accepted Answer

A) K⁺ 
B) Na⁺ 
C) Ca²⁺ 
D) Cl⁻ 
E) H₂O 
A) K⁺ 
B) Na⁺ 
C) Ca²⁺ 
D) Cl⁻ 
E) H₂O

Question 17

Which of the following statements about action potentials is correct?

Accepted Answer

A) Action potentials for a given neuron vary in magnitude. 
B) Action potentials for a given neuron vary in duration. 
C) Action potentials are propagated down the length of the axon. 
D) Movement of ions during the action potential occurs mostly through the Na⁺ pump. 
E) Action potentials of all cells are of the same speed. 
A) Action potentials for a given neuron vary in magnitude. 
B) Action potentials for a given neuron vary in duration. 
C) Action potentials are propagated down the length of the axon. 
D) Movement of ions during the action potential occurs mostly through the Na⁺ pump. 
E) Action potentials of all cells are of the same speed.

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

Question 19

Neural transmission across a mammalian synaptic gap is accomplished by

Accepted Answer

A) the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. 
B) impulses travelling 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. 
A) the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. 
B) impulses travelling 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.

Question 20

Botulinum toxin inhibits the presynaptic release of acetylcholine.If inhibition occurs at a neuromuscular junction,then

Accepted Answer

A) the synaptic cleft will close. 
B) muscle contraction will cease. 
C) the post-synaptic cell will die. 
D) muscles will spasm. 
E) receptor ion channels will remain open. 
A) the synaptic cleft will close. 
B) muscle contraction will cease. 
C) the post-synaptic cell will die. 
D) muscles will spasm. 
E) receptor ion channels will remain open.

Exam 48: Neurons,Synapses,and Signalling

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

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

What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?

The "undershoot" phase of after-hyperpolarization is due to

Saltatory conduction is a term applied to

The heart rate decreases in response to the arrival of

Which of the following will increase the speed of an action potential moving down an axon? I.larger diameter axons. II.lack of potassium ion channels. III.myelinated axons.

Which is the correct order for processing and integrating sensory stimuli?

The operation of the sodium-potassium "pump" moves

Ionotropic receptors are found at synapses operated via

Neurotransmitters affect postsynaptic cells by

If you experimentally increase the concentration of Na⁺ outside a cell while maintaining other ion concentrations as they were,what would happen to the cell's membrane potential?

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

Which of the following ions is most likely to cross the plasma membrane of a resting neuron?

Which of the following statements about action potentials is correct?

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

Neural transmission across a mammalian synaptic gap is accomplished by

Botulinum toxin inhibits the presynaptic release of acetylcholine.If inhibition occurs at a neuromuscular junction,then

Introduction: Evolution and Themes of Biology

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