Deck 39: Information Flow and the Neuron

Question 1

Which glial cells serve as electrical insulators?

A) Schwann cells
B) oligodendrocytes
C) astrocytes
D) interneurons
E) Schwann cells and oligodendrocytes

Answer 1

E

Question 2

Cells in the nervous system that send and receive electrical signals are called ____.

A) receptors
B) neurons
C) sensors
D) glial cells
E) signal cells

Answer 2

B

Question 3

If a drug binds irreversibly to a postsynaptic receptor to prevent the binding of an excitatory neurotransmitter, what is the most likely result?

A) an increased number of IPSPs
B) an increased number of EPSPs
C) a prolonged hyperpolarization
D) a decreased number of IPSPs
E) a decreased number of EPSPs

Answer 3

E

Question 4

Which component of a neural signaling pathway sorts and interprets messages?

A) response
B) integration
C) transmission
D) reception
E) action

Question 5

What characterizes projection neurons?

A) forming many branches near the tip
B) communicating with other nearby neurons
C) Axons extending far from the cell body
D) forming many branches near the cell body
E) both forming many branches near the tip and axons extending far from the cell body

Question 6

Which cells assist and nourish neurons that transmit electrical signals?

A) receptor cells
B) neurons
C) effector cells
D) glial cells
E) signal cells

Question 7

Which part of the neuron conducts the electrical signals away from the cell body of a neuron?

A) axon terminal
B) axon
C) axon hillock
D) nucleus
E) dendrites

Question 8

Which process is responsible for the release of neurotransmitters from the presynaptic neuron into the synapse?

A) diffusion
B) endocytosis
C) exocytosis
D) fusion
E) synaptic release

Question 9

Where are most synapses formed?

A) on the dendrites of postsynaptic neurons
B) on cell bodies
C) on axon terminals
D) on oligodendrocytes
E) on Schwann cells

Question 10

If a drug inhibits the uptake of an excitatory neurotransmitter after it has been released into the synaptic cleft, what is the most likely result?

A) an increased number of IPSPs
B) an increased number of EPSPs
C) a prolonged hyperpolarization
D) a decreased number of IPSPs
E) a decreased number of EPSPs

Question 11

In the context of the nervous system, what does the term "nucleus" mean?

A) a cluster of EPSPs converging on an axonal hillock
B) a cluster of IPSPs converging on an axonal hillock
C) a cluster of axon terminals converging on a single neuron
D) a cluster of dendrites centralized on a single neuron
E) a cluster of neurons with a related function

Question 12

What is(are) the name(s) for the thin, membrane-enclosed tubes that protrude from the neuron cell body and extend long distances away?

A) nerve fibers
B) dendrites
C) axons
D) both dendrites and axons
E) all of these are correct

Question 13

Otto Loewi demonstrated that neurons transmit signals across synapses by ____.

A) electrical signals
B) calcium channels
C) acetylcholine
D) chemical signals
E) proteins

Question 14

Which type of glial cell provides physical support to neurons?

A) Schwann cells
B) astrocytes
C) oligodendrocytes
D) dendrites
E) axons

Question 15

About how far do dendrites extend from the cell body in most neurons?

A) 1 nm
B) 1 cm
C) 1 mm
D) 5 mm
E) 10 mm

Question 16

If a drug binds to a receptor, which normally triggers the opening of a Na⁺channel, causing it to open in the absence of neurotransmitter release, what is the most likely result?

A) an increased number of IPSPs
B) an increased number of EPSPs
C) a prolonged hyperpolarization
D) a decreased number of IPSPs
E) a decreased number of EPSPs

Question 17

In what type of neuron does the axon form many branches close to the cell body?

A) projection neuron
B) dendritic tree
C) interneuron
D) motor neuron
E) astrocyte

Question 18

Which category of organic macromolecule allows myelinated sheaths to act as electrical insulators?

A) proteins
B) carbohydrates
C) lipids
D) RNA
E) DNA

Question 19

Which sequence of the neural signaling pathway is correctly arranged from the earliest to the latest event as it occurs in the nervous system?

A) integration, response, reception
B) response, reception, integration
C) reception, response, integration
D) reception, integration, response
E) integration, reception, response

Question 20

In an electrical synapse, an electrical signal is communicated between two cells via ____ through ____.

A) ion flow; the synaptic cleft
B) neurotransmitter flow; the synaptic cleft
C) neurotransmitter flow; gap junctions
D) ion flow; gap junctions
E) exocytosis; the plasma membrane

Question 21

For a neuron at rest, there is a higher concentration of ____ outside the cell than inside.

A) Na⁺
B) K⁺
C) Ca²⁺
D) anions
E) ATP

Question 22

Depolarization of the neuronal plasma membrane occurs due to ____.

A) the diffusion of K⁺into the cell
B) the diffusion of K⁺out of the cell
C) the diffusion of Na⁺into the cell.
D) the diffusion of Na⁺out of the cell
E) closed gated channels

Question 23

As the action potential peaks, ____.

A) the activation gates of Na⁺channels close
B) the inactivation gates of Na⁺channels close
C) the activation gates of K⁺channels close
D) the inactivation gates of Na⁺channels close
E) Na⁺/K⁺active transport pumps are activated

Question 24

Figure 39.1 (questions 37-40)
Answer the question using the accompanying figure. At which point in this action potential diagram are Na⁺inactivation gates opening?

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

Question 25

When threshold potential is reached, ____.

A) the activation gates of Na⁺channels open
B) the inactivation gates of Na⁺channels open
C) the activation gates of K⁺channels open
D) the inactivation gates of Na⁺channels open
E) Na⁺/K⁺active transport pumps are activated

Question 26

What is the typical resting potential of an isolated neuron?

A) -60 mV
B) -70 mV
C) -80 mV
D) -90 mV
E) 100 mV

Question 27

When measuring membrane potential, the tip of a microelectrode is inserted into a(n) ____.

A) axon
B) node of Ranvier
C) Schwann cell
D) dendrite
E) glial cell

Question 28

Answer the question using the accompanying figure. At which point in this action potential diagram does the K⁺channel close to stabilize the membrane potential?

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

Question 29

During an action potential, the membrane potential can reach as high as ____.

A) -10 mV
B) 0 mV
C) +10 mV
D) +20 mV
E) +30 mV

Question 30

When a neuron membrane potential becomes less negative, it is said to be ____.

A) depolarized
B) hyperpolarized
C) repolarized
D) damaged
E) activated above the threshold potential

Question 31

In an effort to determine the mechanism of neuronal signaling, Otto Loewi isolated ____.

A) frog hearts
B) frog brains
C) rat hearts
D) rat brains
E) rat vagus nerve

Question 32

Answer the question using the accompanying figure. At which point in this action potential diagram are many Na⁺activation gates open and K⁺activation gates closed?

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

Question 33

If the K⁺channels of an excitable plasma membrane were blocked by the action of a drug, which process(es) would be disrupted?

A) repolarization
B) depolarization
C) hyperpolarization
D) repolarization and depolarization
E) repolarization and hyperpolarization

Question 34

Answer the question using the accompanying figure. At which point in this action potential diagram does the onset of Na⁺channel inactivation stop the inward flow of Na⁺?

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

Question 35

The refractory period of a neuronal plasma membrane is important because it ____.

A) establishes the resting potential
B) initiates an action potential
C) ensures that the threshold potential will be reached
D) ensures that an impulse will travel in a one-way direction
E) resets the threshold potential

Question 36

When a neuron membrane potential goes below its resting value it becomes ____.

A) depolarized
B) hyperpolarized
C) repolarized
D) damaged
E) restimulated

Question 37

Calculate E_Nafor a neuron that has an extracellular concentration of Na⁺of 78 mM and an intracellular concentration of Na⁺of 6 mM.

A) -68.0 mV
B) -1.14 mV
C) 1.14 mV
D) 31.6 mV
E) 68.0 mV

Question 38

An abrupt and transient change in membrane potential is called a(n) ____.

A) electrical potential
B) refractory potential
C) threshold potential
D) resting potential
E) action potential

Question 39

The Nernst equation is used to calculate the ____.

A) action potential
B) equilibrium potential
C) membrane potential of a neuron at rest
D) membrane potential of a hyperpolarized neuron
E) membrane potential of a depolarized neuron

Question 40

The minimum level of depolarization required to initiate an action potential in an excitable cell is called the ____ potential.

A) electrical
B) refractory
C) membrane
D) resting
E) threshold

Question 41

The binding of a neurotransmitter to ligand-gated Cl- channels will cause ____ in the postsynaptic membrane.

A) depolarization only
B) hyperpolarization
C) repolarization only
D) apolarization
E) depolarization and repolarization

Question 42

Jean-Luc Eiselé and his coworkers used ______ receptors in their research on neurotransmitter receptor function.

A) African clawed frog
B) toad
C) artificial
D) dog
E) human

Question 43

The spaces between adjacent Schwann cells are called ____.

A) nodes of Ranvier
B) axon terminals
C) dendrites
D) intercalated discs
E) active gaps

Question 44

^{The neurotransmitter receptor research of Jean-Luc Eiselé and his coworkers showed that ____.}

A) neurotransmitters are dependent on the activity of Na⁺
B) neurotransmitters are dependent on the activity of K⁺
C) neurotransmitters are dependent on the activity of Cl
D) neurotransmitters are dependent on the activity of Ca⁺
E) the parts of a receptor binding a neurotransmitter and conducting ions function independently

Question 45

When a fist clenches to grasp a pencil, which neurotransmitter is most likely involved?

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

Question 46

The binding of a neurotransmitter to ligand-gated K⁺channels will cause ____ in the postsynaptic membrane.

A) depolarization only
B) hyperpolarization
C) repolarization only
D) apolarization
E) depolarization and repolarization

Question 47

Action potentials are propagated in a one-way direction down a neuronal plasma membrane because

A) the action potential is of insufficient intensity to stimulate the voltage-gated ion channels behind it
B) the adjacent channels upstream from the action potential are ligand-gated
C) the adjacent channels upstream from the action potential are in a refractory period
D) voltage-gated ion channels are suppressed
E) the adjacent channels upstream from the action potential are at their threshold potential

Question 48

Place the events in chemical synapse transmission in the correct order. (1)   Ca²⁺enters axon terminal.
(2)  Ligand-gated ion channels open in postsynaptic membrane.
(3)   Neurotransmitter binds to postsynaptic receptor.
(4)   Action potential reaches axon terminal of presynaptic neuron.
(5)   Neurotransmitter released by exocytosis.

A) 4, 1, 5, 3, 2
B) 4, 3, 1, 5, 2
C) 4, 5, 1, 3, 2
D) 4, 1, 3, 5, 2
E) 4, 5, 2, 3, 1

Question 49

When an action potential reaches the axon terminal, the ____ channels are activated to trigger synaptic vesicle release.

A) voltage-gated Cl^-channels
B) voltage-gated Ca²⁺channels
C) voltage-gated Na⁺channels
D) ligand-gated Cl^-channels
E) ligand-gated Ca²⁺channels

Question 50

What removes Ca²⁺from the inside of an axon terminal of a chemical synapse after an electrical impulse has passed?

A) ion channels
B) active transport pumps
C) passive carrier proteins
D) exocytosis
E) simple diffusion through the plasma membrane

Question 51

An action potential is propagated down an unmyelinated neuronal plasma membrane because it stimulates voltage-gated ____ channels adjacent to it. (Choose the most accurate answer.)

A) Na⁺
B) Ca²⁺
C) K⁺
D) Na⁺and Ca²⁺
E) K⁺and Ca²⁺

Question 52

Action potential propagation is the fastest in ____.

A) a myelinated axon with a small diameter
B) an unmyelinated axon with a small diameter
C) a myelinated axon with a large diameter
D) an unmyelinated axon with a large diameter
E) all myelinated axons regardless of diameter

Question 53

The binding of a neurotransmitter to ligand-gated Na⁺channels will cause ____ in the postsynaptic membrane.

A) depolarization only
B) hyperpolarization
C) repolarization only
D) apolarization
E) depolarization and repolarization

Question 54

The duration of an action potential is approximately five ____.

A) microseconds
B) milliseconds
C) centiseconds
D) seconds
E) nanoseconds

Question 55

In vertebrates, the neurotransmitter acetylcholine ____.

A) can act as a direct neurotransmitter between neurons and muscle cells
B) is involved in memory and learning
C) can be released into the circulation and act as a hormone
D) can act as a pain reducer and initiate euphoria
E) is involved in pain perception

Question 56

The magnitude of an action potential ____ as it is propagated down an excitable membrane due to the ____ principle.

A) increases; all-or-nothing
B) remains constant; all-or-nothing
C) increases; threshold
D) remains constant; threshold

Question 57

Which neurotransmitter is most likely to be inhibitory?

A) glutamate
B) dopamine
C) Substance P
D) GABA
E) acetylcholine

Question 58

The intensity of an electrical impulse is reflected in the ____ of action potentials.

A) frequency
B) magnitude
C) duration
D) intensity
E) the frequency and duration

Question 59

What will be the effect of a drug that prevents the release of intracellular calcium?

A) a decreased number of IPSPs
B) a decreased number of EPSPs
C) a prolonged hyperpolarization
D) increased neurotransmitter release
E) decreased neurotransmitter release

Question 60

Neuropeptide neurotransmitters ____.

A) can act as direct neurotransmitters between neurons and muscle cells
B) can act as postsynaptic membrane inhibitors
C) directly open K⁺channels to inhibit neurons
D) can act as pain reducers and initiate euphoria
E) directly inhibit euphoria

Question 63

To which class of neurotransmitters does dopamine belong?

A) acetylcholine
B) monoamines
C) amino acids
D) neuropeptides
E) gaseous neurotransmitters

Question 64

Which neuronal structure has the greatest density of voltage-gated Na⁺channels, resulting in the lowest threshold potential along a neuron?

A) dendrites
B) cell body
C) axon hillock
D) axon
E) axon terminals

Question 66

Assume a neuron receives EPSPs and IPSPs from several adjacent neurons. How might that neuron's threshold potential be reached, causing it to produce its own action potential?

A) if IPSPs outnumber EPSPs
B) if IPSPs equal EPSPs
C) if EPSPs outnumber IPSPs
D) if the adjacent neurons contain many axon terminals
E) if the receiving neuron contains many dendrites

Question 67

To which class of neurotransmitters does substance P belong?

A) acetylcholine
B) monoamines
C) amino acids
D) neuropeptides
E) gaseous neurotransmitters

Question 68

Neurotransmitters that bind to G-protein-coupled receptors act more rapidly than those binding to ionotropic receptors.

Question 69

After burning your hand on a hot burner, which neurotransmitter will most likely be released from the pain receptors?

A) glutamate
B) dopamine
C) substance P
D) GABA
E) acetylcholine

Question 70

In terms of changes in membrane potential, compare and contrast action potentials and graded potentials.

Question 71

A graded, subthreshold change in the postsynaptic membrane potential that moves it toward threshold is called a(n) ____.

A) IPSP
B) hyperpolarization
C) EPSP
D) depolarization
E) repolarization

Question 72

Saltatory conduction is the slowest form of action potential propagation.

Question 73

Most neurons that release GABA and glycine are ____.

A) astrocytes
B) projection neurons
C) interneurons
D) oligodendrocytes
E) Schwann cells

Question 74

To which class of neurotransmitters does glutamate belong?

A) acetylcholine
B) monoamines
C) amino acids
D) neuropeptides
E) gaseous neurotransmitters

Question 75

Depolarization occurs due to the diffusion of K⁺across a neuron plasma membrane.

Question 76

Approximately how many neurons comprise the human brain?

A) 1,000
B) 50,000
C) 100,000
D) 75,000,000
E) 86,000,000,000

Question 77

The additive effect of one neuron sending many EPSPs to another neuron over a brief period of time is called spatial summation .

Question 78

At which neuronal structure does summation occur?

A) dendrites
B) cell body
C) axon hillock
D) Schwann cells
E) axon terminals

Question 79

Neurotransmitters are stored in vesicles located within axon terminals .

Question 80

A toxin interferes with the opening of Na⁺channels in the postsynaptic membrane so they open more slowly when bound to a neurotransmitter. What effect would there be on action potential formation in the postsynaptic membrane?