Question 1

After the depolarization phase of an action potential,the resting potential is restored by

Accepted Answer

A) the opening of voltage-gated sodium channels. 
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. 
A) the opening of voltage-gated sodium channels. 
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.

Question 2

The following steps refer to various stages in transmission at a chemical synapse.
1)Neurotransmitters bind with receptors associated with the postsynaptic membrane.
2)Calcium ions rush into the 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 neurotransmitters into the synaptic cleft.
Which sequence of events is correct?

Accepted Answer

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 
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

Question 3

Why are action potentials usually conducted in one direction?

Accepted Answer

A) Ions can flow along the axon in only one direction. 
B) Voltage-gated Na+ channels are inactivated during the refractory period. 
C) The axon hillock has a higher membrane potential than the terminals of the axon. 
D) Voltage-gated channels for both Na+ and K+ open in only one direction. 
A) Ions can flow along the axon in only one direction. 
B) Voltage-gated Na+ channels are inactivated during the refractory period. 
C) The axon hillock has a higher membrane potential than the terminals of the axon. 
D) Voltage-gated channels for both Na+ and K+ open in only one direction.

Question 4

A graded hyperpolarization of a membrane can be induced by

Accepted Answer

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 Ca2+. 
E) increasing its membrane's permeability to K+. 
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 Ca2+. 
E) increasing its membrane's permeability to K+.

Question 5

When mice feel pain on their bodies,they lick that part of their body.Researchers injected bark scorpion venom into the hind paws of the common house mouse and the southern grasshopper mouse;they also injected 0.9% saline (essentially salt water)as a control.The researchers then observed how long the mice licked their paws.Which of the data sets depicted below do you think the researchers collected?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
A) A 
B) B 
C) C 
D) D

Question 6

The nervous system can alter the activities of skeletal muscle fibers because

Accepted Answer

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. 
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.

Question 7

Most of the neurons in the human brain are

Accepted Answer

A) sensory neurons. 
B) motor neurons. 
C) interneurons. 
A) sensory neurons. 
B) motor neurons. 
C) interneurons.

Question 8

________ occurs when several inhibitory postsynaptic potentials (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.

Accepted Answer

A) Temporal summation 
B) Spatial summation 
C) A normal action potential 
A) Temporal summation 
B) Spatial summation 
C) A normal action potential

Question 9

Alexander disease is a type of leukodystrophy in which myelin sheaths surrounding axons in the brain are destroyed.What type of cell is affected,and what is the outcome in Alexander disease?

Accepted Answer

A) Schwann cells are affected,and action potential propagation is slowed. 
B) Oligodendrocytes are affected,and action potential propagation is slowed. 
C) Schwann cells are affected,and action potential propagation is sped up. 
D) Oligodendrocytes are affected,and action potential propagation is sped up. 
A) Schwann cells are affected,and action potential propagation is slowed. 
B) Oligodendrocytes are affected,and action potential propagation is slowed. 
C) Schwann cells are affected,and action potential propagation is sped up. 
D) Oligodendrocytes are affected,and action potential propagation is sped up.

Question 10

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 when it moves from the dendritic region to the axon terminal. 
C) the 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 when it moves from the dendritic region to the axon terminal. 
C) the 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 11

Assume that excessive consumption of ethanol increases the influx of negative chloride ions into "commonsense" 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

Accepted Answer

A) increased membrane depolarization of "commonsense" neurons. 
B) increased membrane hyperpolarization of "commonsense" neurons. 
C) more action potentials in your "commonsense" neurons. 
D) more EPSPs in your "commonsense" neurons. 
E) fewer IPSPs in your "commonsense" neurons. 
A) increased membrane depolarization of "commonsense" neurons. 
B) increased membrane hyperpolarization of "commonsense" neurons. 
C) more action potentials in your "commonsense" neurons. 
D) more EPSPs in your "commonsense" neurons. 
E) fewer IPSPs in your "commonsense" neurons.

Question 12

Please use the following information to answer the questions below.
Curare is a potent neurotoxin extracted from the Strychnos toxifera plant in Central and South America.Indigenous peoples of South America apply curare to arrows,which they used to hunt and kill animals.Curare acts at synapses between motor neurons and skeletal muscle cells.When a motor neuron synapses with a skeletal muscle cell,the skeletal muscle cell may be stimulated or inhibited just like postsynaptic neurons are.Curare acts by binding temporarily to acetylcholine receptors on the postsynaptic cell and prevents acetylcholine from binding.
-What effect does curare likely have on the postsynaptic cell?

Accepted Answer

A) It prevents voltage-gated sodium channels from opening. 
B) It hyperpolarizes the postsynaptic cell. 
C) It stimulates muscle contraction. 
D) It depolarizes the presynaptic cell. 
A) It prevents voltage-gated sodium channels from opening. 
B) It hyperpolarizes the postsynaptic cell. 
C) It stimulates muscle contraction. 
D) It depolarizes the presynaptic cell.

Question 13

An action potential can start in the middle of an axon and proceed to 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. 
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.

Question 14

Researchers injected bark scorpion venom in mouse neurons (both a common house mouse and the southern grasshopper mouse)and measured how many action potentials were generated after the venom was introduced.Their data are shown below.   Based on these data,what effect do you think the venom is having on the grasshopper mouse?

Accepted Answer

A) The venom is blocking voltage-gated sodium channels. 
B) The venom is blocking voltage-gated potassium channels. 
C) The venom is opening voltage-gated sodium channels. 
D) The venom is opening voltage-gated potassium channels. 
A) The venom is blocking voltage-gated sodium channels. 
B) The venom is blocking voltage-gated potassium channels. 
C) The venom is opening voltage-gated sodium channels. 
D) The venom is opening voltage-gated potassium channels.

Question 15

The "threshold" potential of a membrane is the

Accepted Answer

A) maximum depolarization needed to operate sodium-potassium pumps. 
B) lowest frequency of action potentials a neuron can produce. 
C) minimum hyperpolarization needed to prevent the occurrence of action potentials. 
D) minimum depolarization needed to operate the voltage-gated sodium and potassium channels. 
E) peak amount of depolarization seen in an action potential. 
A) maximum depolarization needed to operate sodium-potassium pumps. 
B) lowest frequency of action potentials a neuron can produce. 
C) minimum hyperpolarization needed to prevent the occurrence of action potentials. 
D) minimum depolarization needed to operate the voltage-gated sodium and potassium channels. 
E) peak amount of depolarization seen in an action potential.

Question 16

What will happen if a neuron membrane suddenly becomes permeable to chloride ions?

Accepted Answer

A) Chloride ions will enter the neuron,and the membrane potential will become more negative. 
B) Chloride ions will enter the neuron,and the membrane potential will become more positive. 
C) Chloride ions will exit the neuron,and the membrane potential will become more negative. 
D) Chloride ions will exit the neuron,and the membrane potential will become more positive. 
A) Chloride ions will enter the neuron,and the membrane potential will become more negative. 
B) Chloride ions will enter the neuron,and the membrane potential will become more positive. 
C) Chloride ions will exit the neuron,and the membrane potential will become more negative. 
D) Chloride ions will exit the neuron,and the membrane potential will become more positive.

Question 17

Neurons can be classified according to structure as well as function.If a neuron has a single projection from the cell body,it is a unipolar neuron.If it has two projections,it is a bipolar neuron.Finally,if it has more than two projections,it is a multipolar neuron.What structural type of neuron is an interneuron?

Accepted Answer

A) unipolar neuron 
B) bipolar neuron 
C) multipolar neuron 
A) unipolar neuron 
B) bipolar neuron 
C) multipolar neuron

Question 18

A synapse is

Accepted Answer

A) a single long extension off the cell body of a neuron. 
B) the point of connection between two communicating neurons. 
C) one of many extensions off a cell body that receives signals from other neurons. 
D) the location where action potentials are generated. 
A) a single long extension off the cell body of a neuron. 
B) the point of connection between two communicating neurons. 
C) one of many extensions off a cell body that receives signals from other neurons. 
D) the location where action potentials are generated.

Question 19

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 20

Please use the following information to answer the questions below.
Tetraethylammonium (TEA)is a potent neurotoxin that results in death from respiratory failure within 10 to 30 minutes.When a neuron is incubated with TEA,researchers observed that action potentials could be generated,but the membrane potential remained positive and never returned to the resting membrane potential.
-What channels could be opened that would counter the effects of TEA and allow the neuron to return to resting membrane potential?

Accepted Answer

A) chloride channels 
B) calcium channels 
C) sodium channels 
D) There are no channels that can oppose the effects of TEA. 
A) chloride channels 
B) calcium channels 
C) sodium channels 
D) There are no channels that can oppose the effects of TEA.

Exam 37: Neurons,synapses,and Signaling

After the depolarization phase of an action potential,the resting potential is restored by

Why are action potentials usually conducted in one direction?

A graded hyperpolarization of a membrane can be induced by

The nervous system can alter the activities of skeletal muscle fibers because

Most of the neurons in the human brain are

________ occurs when several inhibitory postsynaptic potentials (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.

Alexander disease is a type of leukodystrophy in which myelin sheaths surrounding axons in the brain are destroyed.What type of cell is affected,and what is the outcome in Alexander disease?

Saltatory conduction is a term applied to

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

The "threshold" potential of a membrane is the

What will happen if a neuron membrane suddenly becomes permeable to chloride ions?

A synapse is

The heart rate decreases in response to the arrival of

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