Deck 41: Neural Signaling

Question 1

Figure 41-1 Refer to the accompanying figure. The absence of structures represented by label 6 would result in:

A) increased speed of impulse transmission
B) decreased speed of impulse transmission
C) enhanced saltatory conduction
D) complete loss of impulse transmission
E) complete loss of neurotransmitter release

Answer 1

B

Question 2

During a relative refractory period, ____.

A) an axon can transmit impulses comparable to a resting neuron.
B) an axon cannot transmit an action potential.
C) an axon can transmit impulses, but the threshold level is higher.
D) an axon can transmit impulses, but the threshold level is lower.
E) all voltage-activated sodium channels are inactivated.

Answer 2

C

Question 3

Which is an accurate statement regarding the structure of a neuron?

A) Dendrites carry impulses away from the cell body.
B) Nodes of Ranvier are gaps between myelinated axon segments.
C) Nerve impulses travel along the axon toward the cell body.
D) Dendrites are often myelinated for faster conduction.
E) Myelin is a fatty material produced and secreted by the axon.

Answer 3

B

Question 4

Figure 41-1 Refer to the accompanying figure. What is the function of the structure labeled as 4?

A) To insulate the axon
B) To release neurotransmitters
C) To synthesize cell body organelles
D) To receive inputs from other neurons
E) To send retrograde signals to the cell body

Question 5

Figure 41-2 Refer to the accompanying figure. What structure is designated by label B?

A) activation gate
B) inactivation gate
C) modulatory sensor
D) transport pump
E) transport sensor

Question 6

The function of the sodium-potassium pump is to actively move:

A) sodium into the cell and potassium out of the cell
B) sodium out of the cell and potassium into the cell
C) sodium out of the cell and to block potassium movement
D) both sodium and potassium out of the cell
E) both sodium and potassium into the cell

Question 7

Saltatory conduction:

A) does not involve voltage-activated potassium ion channels.
B) can occur in both myelinated and unmyelinated neurons.
C) is slightly slower than continuous conduction.
D) is more energy efficient than continuous conduction.
E) allows nerve impulses to jump from Schwann cell to Schwann cell.

Question 8

What happens when the membrane potential of a neuron reaches the threshold level?

A) Voltage-gated sodium channels open, and sodium diffuses out of the cell.
B) Voltage-gated potassium channels open for a very brief period.
C) Voltage-gated sodium channels close, so sodium cannot diffuse out of the cell.
D) The sodium channel protein changes its shape to open the gates of the channel.
E) The membrane potential is more negative than when at rest.

Question 9

One function performed by astrocytes is to:

A) form myelin sheaths
B) induce synapse formation
C) circulate cerebral spinal fluid
D) phagocytize bacteria
E) transmit action potentials

Question 10

Neural signaling typically involves four processes. What is the correct order of those processes?

A) integration, reception, action by effectors, and transmission
B) reception, transmission, integration, and action by effectors
C) integration, transmission, reception, and action by effectors
D) action by effectors, transmission, integration, and reception
E) reception, integration, action by effectors, and transmission

Question 11

Figure 41-2 The accompanying figure represents a sequence of events occurring in the neuronal membrane (designated by the numbers 1 and 2). The letter "I" indicates an ion. What event is mostly likely being portrayed in this figure?

A) activation of voltage-gated sodium channels
B) activation of voltage-gated potassium channels
C) activation of voltage-gated chloride channels
D) activation of sodium-chloride pumps
E) activation of sodium-potassium pumps

Question 12

What is a neuronal attribute that contributes to the resting membrane potential?

A) Potassium is kept at a high concentration outside the cell compared with the inside.
B) Sodium is kept at a high concentration inside the cell compared with the outside.
C) Neurons are more permeable to sodium than they are to potassium.
D) The cytosol contains large molecules that have a net positive charge.
E) The cytosol contains large molecules that have a net negative charge.

Question 13

Which of the following statements about the speed of impulse conduction in a neuron is true?

A) Longer axons can transmit impulses faster than shorter ones.
B) Unmyelinated axons transmit impulses faster than myelinated ones.
C) Shorter axons can transmit impulses faster than longer ones.
D) Nerve impulses travel faster than the speed of light.
E) Unmyelinated axons with larger diameters transmit impulses faster than ones with small diameters.

Question 14

What axonal characteristic facilitates the propagation of an action potential along a myelinated axon?

A) Voltage-gated Na⁺ and K⁺ channels are concentrated in the myelinated axonal segments.
B) Voltage-gated Na⁺ and K⁺ channels are concentrated in the unmyelinated axonal segments.
C) Voltage-gated Na⁺ channels are concentrated in the myelinated axonal segments; voltage-gated K⁺ channels are concentrated in the unmyelinated axonal segments.
D) Voltage-gated K⁺ channels are concentrated in the myelinated axonal segments; voltage-gated Na⁺channels are concentrated in the unmyelinated axonal segments.
E) Voltage-gated Na⁺ K⁺ channels are spread evenly throughout both myelinated and unmyelinated segments.

Question 15

Figure 41-1 Refer to the accompanying figure. Which structure integrates incoming signals?

A) 2
B) 4
C) 5
D) 6
E) 8

Question 16

Which neural signaling process is correctly paired with its function?

A) integration: sort and interpret sensory information
B) reception: sort and interpret sensory information
C) transmission: sort and interpret sensory information
D) integration: detect a stimulus
E) transmission: detect a stimulus

Question 17

In multiple sclerosis, a patient:

A) loses coordination due to the replacement of myelin with scar tissue.
B) accumulates neurofibrillary tangles in the brain resulting in dementia.
C) suffers tremors due to overly rapid and spontaneous firing of neural impulses.
D) loses the ability to move because of motor neuron degeneration.
E) suffers depression due to abnormal secretion of neurotransmitters.

Question 18

The myelin sheath:

A) is a protein covering around dendrites.
B) is responsible for integrating information.
C) is a fatty covering only around axons.
D) stores neurotransmitters in the axon.
E) is a fatty covering only around cell bodies.

Question 19

Which neurons integrate information coming into and out of the central nervous system?

A) afferent neurons
B) motor neurons
C) interneurons
D) efferent neurons
E) sensory neurons

Question 20

Figure 41-1 Refer to the accompanying figure. Which structure is specialized to receive stimuli from other neurons and to send signals to the cell body?

A) 1
B) 4
C) 6
D) 7
E) 9

Question 21

Figure 41-3 Step 2 in the accompanying figure is accomplished by an influx of:

A) Ca²⁺
B) Na²⁺
C) K⁺
D) Na²⁺
E) K⁺

Question 22

Since all action potentials are identical, the intensity of a sensation depends on:

A) whether a myelinated or unmyelinated neuron has been stimulated.
B) the duration of the stimulation.
C) whether the neuron stimulated is a pre- or postsynaptic neuron.
D) the total number of neurons stimulated and the frequency of their discharge.
E) the presence of an EPSP or IPSP, which allows for a graded response.

Question 23

Figure 41-3 Refer to the accompanying figure. Depolarization is indicated by the label:

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

Question 24

What is a characteristic of the all-or-none response?

A) If a stimulus is strong enough, all axons in a nerve bundle will fire simultaneously.
B) A neuron will only produce an action potential if it has been depolarized to its threshold level.
C) All neurons of a nerve bundle discharge impulses at the same frequency.
D) A neuron can create an action potential of varying intensities.
E) Either all or none of the neurons of a brain region will fire impulses when stimulated.

Question 25

Which molecule acts as a retrograde messenger at many synapses?

A) GABA
B) glycine
C) serotonin
D) substance P
E) nitric oxide

Question 26

Figure 41-3 In the accompanying figure, label A represents:

A) resting state.
B) repolarization
C) threshold level.
D) equilibrium potential.
E) hyperpolarization.

Question 27

What did Alan Hodgkin and Andrew Huxley conclude from their squid axon experiments?

A) The passage of Na⁺ ions into a neuron and K⁺ ions out of a neuron results in an action potential.
B) The passage of K⁺ ions into a neuron and Na⁺ ions out of a neuron results in an action potential.
C) The passage of K⁺ ions into a neuron and Ca⁺ ions out of a neuron results in an action potential.
D) The passage of Cl^- ions into a neuron and K⁺ ions out of a neuron results in an action potential.
E) The passage of Cl^- ions into a neuron and Ca⁺ ions out of a neuron results in an action potential.

Question 28

What event begins the process of repolarization following an action potential?

A) K⁺ channel inactivation gates close.
B) K⁺ channel inactivation gates open.
C) Na⁺ channel activation gates open.
D) Na⁺ channel activation gates close.
E) Na⁺ channel inactivation gates close.

Question 29

Which molecule is the major excitatory neurotransmitter in the brain?

A) GABA
B) glutamate
C) serotonin
D) dopamine
E) acetylcholine

Question 30

In a neuron, a graded potential:

A) does not vary in magnitude.
B) becomes stronger as it propagates.
C) only generates slow action potentials.
D) fades out within a few millimeters.
E) propagates only along unmyelinated axons.

Question 31

Which statement about chemical or electrical synapses is true?

A) Electrical synapses require a neurotransmitter.
B) In electrical synapses, presynaptic and postsynaptic neurons are separated by synaptic clefts.
C) Electrical synapses store excess ions in synaptic vesicles.
D) In chemical synapses, presynaptic and postsynaptic neurons are connected by a protein channel.
E) Electrical synapses involve the transfer of ions from presynaptic to postsynaptic neurons.

Question 32

Many neurotransmitter receptors are chemically activated ion channels known as:

A) ligand-gated channels.
B) metabotropic channels.
C) voltage-gated channels.
D) G protein-coupled channels. .
E) neurotransmitter-selective channels.

Question 33

An inhibitory post-synaptic impulse (IPSP):

A) brings a neuron to a more positive voltage.
B) brings the neuron further away from firing.
C) occurs when Cl^- ion channels close.
D) occurs when Na⁺ ion channels open.
E) occurs when K⁺ ion channels close.

Question 34

In Alzheimer's disease , neurons that secrete which neurotransmitter are particularly affected?

A) epinephrine
B) dopamine
C) serotonin
D) acetylcholine
E) GABA

Question 35

What event triggers the release of neurotransmitters?

A) Calcium induces the fusion of synaptic vesicles with the presynaptic membrane.
B) Sodium induces the fusion of synaptic vesicles with the presynaptic membrane.
C) Potassium induces the fusion of synaptic vesicles with the presynaptic membrane.
D) Calcium activates enzymes that degrade synaptic vesicles.
E) Sodium activates enzymes that degrade synaptic vesicles.

Question 36

Dr. Askins performs an electrophysiology experiment. She records a neuron at rest. What voltage does she record?

A) -70 mV
B) -55 mV
C) +35 mV
D) +55 mV
E) +70 mV

Question 37

Dr. Askins performs an electrophysiology experiment. She records a neuron firing an action potential. What voltage does she record during each action potential spike?

A) -70 mV
B) -55 mV
C) +35 mV
D) +55 mV
E) +70 mV

Question 38

The Japanese puffer fish, a food delicacy, contains the chemical tetrodotoxin (TTX). If too much TTX is ingested, this can prevent breathing because TTX:

A) binds to and activates voltage-activated K⁺ channels.
B) binds to and activates voltage-activated Na⁺ channels.
C) blocks the passage of Ca⁺ through voltage-activated Ca⁺ channels.
D) blocks the passage of Na⁺ through voltage-activated Na⁺ channels.
E) blocks the passage of K⁺ through voltage-activated K⁺ channels.

Question 39

In a resting neuron:

A) the concentration of potassium ions is about 10 times greater inside the cell than in the extracellular fluid.
B) excitatory postsynaptic potentials hyperpolarize the membrane.
C) voltage-activated sodium channels are pumping sodium inside the cell against its concentration gradient.
D) the membrane is more permeable to sodium than potassium ions.
E) inhibitory postsynaptic potentials depolarize the membrane.

Question 40

The resting potential of a neuron results from a:

A) neutral charge in the cytosolic and extracellular fluids.
B) negative cytosolic charge relative to the extracellular fluid.
C) positive cytosolic charge relative to the extracellular fluid.
D) fluctuating cytosolic charge and constant extracellular charge.
E) constant cytosolic charge and fluctuating extracellular charge.

Question 41

In convergence , a single neuron is controlled by signals from two or more presynaptic neurons.
____________________

Question 42

What is/are characteristic(s) of EPSPs and IPSPs?

A) EPSPs and IPSPs do not influence action potentials.
B) EPSPs and IPSPs are graded potentials.
C) EPSPs and IPSPs occur via an all-or-none response.
D) EPSPs are fast action potentials; IPSPs are slow action potentials.
E) EPSPs occur in myelinated axons; IPSPs occur in unmyelinated axons.

Question 43

A neuronal axon transmits neural impulses toward its cell body.
____________________

Question 44

Astrocytes are glia that provide nutrients for neurons.
____________________

Question 45

Spatial summation is characterized by:

A) several presynaptic neurons releasing neurotransmitter simultaneously.
B) several presynaptic neurons releasing neurotransmitter in a sequential pattern.
C) several postsynaptic neurons receive sequential inputs from several presynaptic neurons.
D) a single presynaptic neuron firing multiple times in rapid succession.
E) a single presynaptic neuron directly contacting several postsynaptic neurons.

Question 46

An EPSP is an example of a(n) graded potential.
____________________

Question 47

Arrange the events of a second messenger system in the correct order.
1) Protein kinase is activated.
2) G protein is activated.
3) The neurotransmitter binds to its receptor.
4) The protein closes the potassium channel.
5) Cyclic AMP is produced.
6) Phosphorylation takes place.

A) 1 → 2 → 5 → 6 → 4 → 3
B) 3 → 5 → 6 → 1 → 2 → 4
C) 5 → 2 → 6 → 1 → 3 → 4
D) 3 → 2 → 5 → 1 → 6 → 4
E) 5 → 2 → 6 → 1 → 4 → 3

Question 48

An excitatory postsynaptic potential (EPSP):

A) results in partial depolarization of the neuron.
B) always causes a neuron to fire.
C) prevents a neuron from firing.
D) results in partial hyperpolarization of the neuron.
E) changes the action potential threshold level.

Question 49

In divergence, one neuron:

A) is controlled by several neurons.
B) is controlled by several neurotransmitter substances.
C) contains several different types of ion channels.
D) controls several other neurons.
E) contains several different types of receptors.

Question 50

Draw a diagram of a typical neuron, label its parts, and list the function of each labeled structure.

Question 51

Acetylcholine is a neurotransmitter released from motor neurons.
____________________

Question 52

Describe the sequence of events that lead to neurotransmitter release from a presynaptic neuron.

Question 53

The sodium-potassium pump transports two Na⁺ out of the cell for every two K⁺ transported in.
____________________

Question 54

The resting potential of a typical neuron is approximately +70 mV.
____________________

Question 55

During the absolute refractory period, the axon membrane cannot transmit another action potential.
____________________

Question 56

Compare and contrast the production and transmission of a graded potential with those of an action potential.

Question 57

Neurotransmitters move by active transport across the synaptic cleft.
____________________

Question 58

In a neuron at rest, there is a(n) higher concentration of sodium ions outside the cell than inside.
____________________

Question 59

Ependymal cells are a type of macrophage.
____________________

Question 60

The arrival of an action potential at a synaptic terminal causes voltage-gated potassium channels to open.
____________________

Question 63

Explain the difference between an absolute and a relative refractory period.

Question 64

Why is saltatory conduction faster than continuous conduction?

Question 65

How is summation related to IPSPs and EPSPs? What is the difference between temporal summation and spatial summation?

Question 66

Although the effects of an EPSP are subliminal, explain how EPSPs affect membrane potential.