Deck 22: Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

Question 1

Each of the following contributes to the unidirectional propagation of nerve signals except

A)dendrites only receive signals.
B)presynaptic neurotransmitter secretion is separated from postsynaptic receptors.
C)neuron membranes have a refractory period following generation of an action potential.
D)ion channels are oriented to transport ions only into the neuron.
E)action potentials initiate the hillock and propagate only down the axon.

Answer 1

D

Question 2

-Which point on the graph represents the threshold potential?

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

Answer 2

B

Question 3

Under times of great stress or shock,which of the following neurotransmitters interferes with the perception of pain?

A)endocannabinoids
B)GABA
C)catecholamines
D)enkephalins
E)acetylcholine

Answer 3

D

Question 4

While characterizing the activities of several neurons,you find a neuron with the following properties: (1)When stimulated,the neuron fails to release neurotransmitters into the synaptic cleft.
(2)Microinjection of calcium ions calcium ions has no effect on the neuron.(In other neurons such microinjection stimulates the t-SNARE and v-SNARE complex interaction that promotes neurotransmitter secretion.)
The abnormality in this neuron is most likely associated with the function of

A)the vesicle membranes.
B)acetylcholinesterase.
C)synaptotagmin.
D)GABA receptors.
E)gap junctions.

Question 5

-Based on the graph,how soon could another action potential be easily initiated (at the end of the relative refractory period)after the first stimulus?

A)less than 0.5 msec
B)1 msec
C)2 msec
D)3 msec
E)4 msec

Question 6

The resting potential of a particular nerve cell is −66 mV.Depolarization of the neuron membrane will shift the membrane potential to

A)−90 mV.
B)−75 mV.
C)0 mV.
D)+45 mV.
E)+66 mV.

Question 7

-If myelin was lost from the neuron firing the action potential graphed,the action potential cycle would

A)go much faster than depicted in the graph.
B)go much faster than normal but not peak at 30 mV.
C)go slower than depicted in the graph.
D)go much slower than normal but peak much higher than 30 mV.
E)remain the same.

Question 8

What happens to neurons in the approach known as optogenetics?

A)Mutations to ion channel proteins are corrected.
B)The neurons are made to express light-sensitive ion channels.
C)Neurotransmitter stores are depleted.
D)Fusion of neurotransmitter vesicles to the presynaptic membrane is blocked.
E)Leakage of cytoplasmic polyanions is blocked.

Question 9

Plasma membrane permeability of which of the following ions is most important in generating the resting membrane potential?

A)sodium ions
B)potassium ions
C)chloride ions
D)calcium ions
E)None of the above generates resting membrane potential.

Question 10

-The parts of the graph indicated between points C and E represent

A)depolarization.
B)hyperpolarization.
C)the absolute refractory period.
D)repolarization.
E)sodium channel activity.

Question 11

Each of the following statements about action potentials is true except

A)action potentials are propagated along a dendrite.
B)action potentials require rapid changes in membrane potential.
C)due to ion leaking,membranes may undergo subthreshold depolarization,which is insufficient to produce an action potential.
D)action potentials end with a transient hyperpolarization.
E)the action potential cycle has a refractory period.

Question 12

Which of the following interferes with the reuptake of neurotransmitters?

A)Valium
B)Librium
C)Botox
D)Prozac
E)curare

Question 13

Which of the following is a disease specifically caused by an autoimmune response against acetylcholine receptors?

A)ataxia
B)myasthenia gravis
C)multiple sclerosis
D)tetanus
E)botulism

Question 14

Generation of an action potential by a neuron may ultimately stimulate

A)another nerve cell.
B)skeletal muscle cells.
C)gland cells.
D)smooth muscle cells.
E)All of the above may be stimulated by a signal.

Question 15

Which neurotransmitter is not an amino acid derivative?

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

Question 16

An example of a generally inhibitory neurotransmitter is

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

Question 17

Each of the following is a type of glial cells except

A)interneurons.
B)oligodendrocytes.
C)astrocytes.
D)Schwann cells.
E)microglia cells.

Question 18

The axon branches of a typical neuron terminate at structures called

A)synapses.
B)boutons.
C)glia.
D)nodes of Ranvier.
E)the myelin sheath.

Question 19

-If the membrane represented in the graph was stimulated in the presence of a drug that specifically inhibits sodium channels,the membrane would

A)not depolarize.
B)depolarize for one stimulus but not for a second stimulus.
C)depolarize but not repolarize.
D)repolarize only to the threshold potential.
E)become permanently hyperpolarized.

Question 20

How many neuronal connections are there in the human brain?

A)millions
B)1 billion
C)10 billion
D)100 billion
E)trillions

Question 21

Which of the following are phagocytic glial cells that fight infection and remove debris?

A)microglia
B)oligodendrocytes
C)Schwann cells
D)myelin sheath cells
E)astrocytes

Question 22

A drug that specifically inhibits voltage-gated calcium channels would most directly inhibit

A)depolarization of nerve cell membranes.
B)repolarization after depolarization of nerve cell membranes.
C)hyperpolarization of nerve cell membranes.
D)presynaptic neurotransmitter release.
E)postsynaptic receptor signal response.

Question 23

Although they are smaller than K⁺,Na⁺ ions fail to pass through K⁺ channels because Na⁺

A)is repulsed by positively charged amino acids at the mouth of the channel.
B)is too small to interact with oxygen atoms in amino acids on all sides of the channel and therefore does not completely lose its waters of hydration.
C)is always transported complexes to Cl⁻.
D)is always transported in a complex with two other Na⁺ ions.
E)is attracted by other Na⁺ ions,which are at higher concentration outside than inside the cell.

Question 24

You are examining an organism recently found on Mars and are currently trying to identify one of its neurotransmitters.Biochemical characterization indicates that it is a derivative of the amino acid tyrosine,so you classify the novel neurotransmitter as a(n)

A)acetylcholine analogue.
B)catecholamine.
C)neuropeptide.
D)serotonin analogue.
E)GABA analogue.

Question 25

You have added a specific amount of excitatory neurotransmitter mixed with a 6× higher concentration of an inhibitory neurotransmitter to a synaptic cleft.You expect that the postsynaptic neuron will

A)produce 6× its normal number of action potentials.
B)produce 6× its normal number of negative action potentials.
C)show a net hyperpolarization as a result of neuronal integration.
D)show a net depolarization as a result of neuronal integration.
E)not respond to either signal.

Question 26

Each of the following statements is true about the nicotinic acetylcholine receptor except

A)the actions of acetylcholine can be mimicked by nicotine.
B)it binds one molecule of acetylcholine for activity.
C)the open channel allows an influx of sodium ions.
D)biochemical purification was aided by the use of cobratoxin.
E)it is made up of five large subunits.

Question 27

Each of the following is a correct relationship between action potential phase and channel status except

A)depolarization; Na⁺ channels open.
B)repolarizing phase; Na⁺ channels closed.
C)repolarizing phase; K⁺ channels open.
D)hyperpolarizing phase; Na⁺ channels open.
E)hyperpolarizing phase; K⁺ channels open.

Question 28

Catecholamines are synthesized by the

A)adrenal gland.
B)anterior pituitary gland.
C)skeletal muscle.
D)Schwann cells.
E)hypothalamus.

Question 29

Multiple sclerosis is a result of

A)demyelination of nerve cells.
B)excess myelin on nerve cells.
C)a decrease in postsynaptic receptors.
D)blocking the nodes of Ranvier.
E)proteolytic cleavage of presynaptic SNARE proteins.

Question 30

The intracellular stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in

A)potassium ion levels.
B)chloride ion levels.
C)sodium ion levels.
D)calcium ion levels.
E)acetylcholine levels.

Question 31

The maximum membrane potential that an ion gradient can produce is the

A)action potential.
B)membrane potential.
C)equilibrium potential.
D)threshold potential.
E)resting potential.

Question 32

Sarin nerve gas paralyzes muscle by interfering with neuronal transmission by which of the following?

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

Question 33

Hyperpolarization of the postsynaptic nerve terminal

A)decreases the chance that an action potential will be initiated.
B)increases the chance that an action potential will be initiated.
C)has no effect on the initiation of an action potential.
D)is stimulated by an influx of calcium ions.
E)sensitizes receptors to activation by lower levels of neurotransmitter.

Question 34

Each of the following is a voltage-gated Na⁺ channel property except

A)opens rapidly when stimulated.
B)closes rapidly in absence of stimulus.
C)opens to a variable extent depending on how much the stimulus voltage exceeds the threshold voltage.
D)has a voltage sensor helix that controls channel gating.
E)can be inactivated by the inactivating particle part of the channel protein.

Question 35

Sodium channels are concentrated in the

A)axon hillock and nodes of Ranvier.
B)dendrites and synaptic boutons.
C)dendrites and nodes of Ranvier.
D)dendrites and axon hillock.
E)synaptic boutons and axon hillock.

Question 36

Leak channels make a neuronal membrane at steady state approximately ________ permeable to K⁺ than to Na⁺.

A)half as
B)equally
C)twice as
D)10 times more
E)100 times more

Question 37

Which equation best describes the relationship between an ion gradient and the equilibrium potential that will form when the membrane is permeable to only that ion?

A)Huxley equation
B)Goldman equation
C)Nernst equation
D)Hodgkin equation
E)Katz equation

Question 38

The phase at the end of an action potential when the membrane potential becomes more negative than it is at rest is the ________ phase.

A)threshold
B)depolarizing
C)repolarizing
D)hyperpolarizing
E)refractory

Question 39

________ is a technique used to measure ion currents passing through individual channels along a nerve cell.

Question 40

The technique that can be used to record ion currents passing through individual channels is known as

A)voltage-gating.
B)ligand-gating.
C)patch-clamping.
D)ion sensors.
E)optogenetics.

Question 41

The ________ equation accounts for the movement of a single ion type,while the ________ equation takes into account the movement of multiple ions on membrane potential.

Question 42

Describe the docking and fusion of synaptic vesicles with the cell membrane.Describe the mechanisms by which tetanus toxin and botulinum toxin interfere with this process.

Question 43

Influx of ________ ions initiates neurotransmitter release into the synaptic cleft by the process of ________.

Question 44

________ is an autoimmune disease characterized by the presence of antibodies that bind to and block acetylcholine receptors.

Question 45

At rest,a cell has a ________ charge inside the plasma membrane and a ________ charge outside the plasma membrane.

Question 46

Synaptic vesicles are synthesized in the nerve ________.

Question 47

________ receptors,which act in a(n)________ manner,act more slowly than ionotropic receptors.

Question 48

Tricyclic antidepressants,such as imipramine hydrochloride,have been prescribed for treatment of ADHD (attention deficit hyperactivity disorder)to enhance neural circuit activity because they affect the reuptake of excitatory neurotransmitters.Predict the effect of such drugs on the postsynaptic neuron and explain your rationale.

Question 49

________ carry a signal across the synapse between two adjacent nerve cells.

Question 50

A mammalian neuromuscular junction endplate region at rest has the following concentrations of sodium and potassium: [K⁺]_in = 140 mM,[K⁺]_out = 5 mM,[Na⁺]_in = 10 mM,[Na⁺]_out = 145 mM,[Cl^-]_in = 10 mM,and [Cl^-]_out = 125 mM.What is the membrane potential of this endplate region (at 37°C)?

Question 51

A nerve cell ________ involves a temporary depolarization and repolarization of the cell membrane.

Question 52

Subtypes of acetylcholine receptors can be distinguished by their ability to be activated by substances such as ________ and ________.

Question 53

The ________ receptor is a ligand-gated channel that transports chloride ions.