Deck 13: Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

Question 1

As a result of the way nerve impulses are propagated,they are unidirectional.Which of the following does not contribute to this phenomenon?

A)The time interval encompassed by the refractory period does not allow the impulse to travel in reverse.
B)Presynaptic neurotransmitters and postsynaptic receptors are separated.
C)Unidirectional sodium and potassium channels open only toward the axon of the nerve cell.
D)Sensory processes are oriented in such a manner that the information is targeted to the dendrites of the nerve cell.
E)none of the above

Answer 1

C

Question 2

The resting potential of a particular nerve cell is -66 mV.Depolarization of the membrane will shift the membrane potential toward

A)-90 mV.
B)-66 mV.
C)0 mV.
D)There will be no change.
E)There is not enough information to tell.

Answer 2

C

Question 3

In the graph above,the point at which the potassium channels open is indicated by the letter

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

Answer 3

C

Question 4

A particular neuron does not release neurotransmitters into the synaptic cleft.Further investigation shows that this cell does not respond to calcium ions that are necessary for t- and v-SNARE complex interaction.The most likely problem is associated with the function of

A)synaptic boutons.
B)acetylcholinesterase.
C)synaptotagmin.
D)GABA receptors.
E)calcium ions.

Question 5

The parts of the graph indicated at points C,D,and E represent

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

Question 6

Of all of the ions associated with generating the resting membrane potential,the permeability of the membrane to ________ is the most important.

A)sodium ions
B)potassium ions
C)chloride ions
D)all of the above
E)none of the above

Question 7

Based on the graph above,after approximately what period of time could another impulse be propagated?

A)1 msec
B)2 msec
C)3 msec
D)4 msec
E)immediately following the first stimulation

Question 8

Refer to the graph above.At the same time that the stimulus was introduced,a drug that specifically inhibits sodium channels was added to the system.The effect this would have is that the membrane would

A)not depolarize.
B)depolarize for the first impulse but not for a second one.
C)not be able to repolarize.
D)repolarize, but would not for a second impulse.
E)none of the above

Question 9

The portion of the nervous system that is associated with the control of involuntary activities is the

A)central nervous system.
B)peripheral nervous system.
C)autonomic nervous system.
D)somatic nervous system.
E)automatic nervous system.

Question 10

The sweetener aspartame is a known excitotoxin.With regard to nerve cells,ingestion of this substance results in chronic nerve stimulation.With your knowledge of action potentials,this toxin must

A)stimulate continual impulses at the cell body.
B)stimulate continual impulses at the dendrite.
C)bind the nodes of Ranvier.
D)block the synaptic cleft.
E)stimulate continual impulses at the presynaptic receptors.

Question 11

Refer to the graph above.If the myelin fibers were stripped from this membrane,you would expect the action potential cycle to go

A)much faster than depicted in the graph.
B)much faster than normal but not peak at 30 mV.
C)slower than depicted in the graph.
D)much slower than normal but peak much higher than 30 mV.
E)none of the above

Question 12

Based on your knowledge of nerve transmission,this movement of ions will

A)stimulate a change in a postsynaptic membrane.
B)not stimulate a change in a postsynaptic membrane.
C)stimulate a change in a postsynaptic membrane if three channel events are combined.
D)stimulate a change in a postsynaptic membrane if 50 channel events are combined.
E)generate a current resulting in membrane depolarization.

Question 13

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

A)Grave's disease
B)myasthenia gravis
C)systemic lupus erythematosus
D)Hashimoto's thyroiditis
E)celiac disease

Question 14

The axon branches of a typical neuron terminate at structures called

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

Question 15

In the graph above,at what point in the action potential will the sodium channels be opened?

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

Question 16

Which neurotransmitter is not an amino acid derivative?

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

Question 17

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)enkaphalins
E)calcium ions

Question 18

Based on the graph above,the threshold voltage appears to be approximately

A)60 mV.
B)30 mV.
C)0 mV.
D)-30 mV.
E)-60 mV.

Question 19

All of the following are glial cells except

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

Question 20

An electrical current of 1 A is approximately 6 x 10¹⁸ electrical charges per second; how many ions pass through the channel when it is open?

A)144,000 ions
B)2400 ions
C)8,640,000 ions
D)8640 ions
E)You cannot determine this from the information given.

Question 21

An action potential can always be initiated specifically at which of the following locations associated with a neuron?

A)ion channels
B)synaptic boutons
C)nodes of Ranvier
D)both choices A and B
E)none of the above

Question 22

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

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

Question 23

You are examining a recently captured organism from another planet and are currently trying to deduce the types of neurotransmitters associated with the propagation of nerve impulses.You discover a very interesting neurotransmitter and find that,in spite of being alien,it is a derivative of the amino acid tyrosine.As a result,this novel neurotransmitter has to be classified as a(n)

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

Question 24

You treat an organism with a drug that inhibits calcium permeability in nerve cells specifically.As a result,you expect to see

A)no depolarization of membranes.
B)no repolarization of membranes.
C)failure to achieve the threshold necessary to stimulate a signal.
D)presynaptic neurotransmitter release.
E)no postsynaptic receptors.

Question 25

Exposure to sarin,a potent nerve gas,results in muscle paralysis.Therefore,sarin must interfere with which neurotransmitter?

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

Question 26

Multiple sclerosis is a result of

A)the absence of myelin on nerve cells.
B)excess amounts of myelin on nerve cells.
C)an immune system attack on nerve fibers.
D)blocking the nodes on Ranvier.
E)having excess acetylcholine receptors.

Question 27

The glial cells associated with phagocytosis to fight infection and remove debris are the

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

Question 28

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

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

Question 29

You stimulate a neuron response by adding a given amount of excitatory neurotransmitter mixed with a 6x higher concentration of an inhibitory neurotransmitter to the synaptic cleft.You expect that

A)excitatory responses will travel 1/6 as often as inhibitory ones.
B)inhibitory responses will travel 1/6 as often as excitatory ones.
C)as a result of neuronal integration, there will be an inhibitory signal.
D)as a result of neuronal integration, there will be an excitatory signal.
E)the neuron will be confused and will not respond to the signal.

Question 30

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 31

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)does not affect the initiation of an action potential.
D)is stimulated by an influx of calcium ions.
E)none of the above

Question 32

An example of an inhibitory neurotransmitter is

A)acetylcholine.
B)epinephrine.
C)dopamine.
D)GABA.
E)insulin.

Question 33

Which of the following drugs interferes with the reuptake of neurotransmitters in order to have its desired clinical effect?

A)Valium
B)Librium
C)pyridostigmine
D)Prozac
E)acetaminophen

Question 34

Catecholamines are synthesized by the

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

Question 35

Which equation best describes the relationship between ion gradient and equilibrium potential for that ion?

A)steady-state
B)Goldman
C)Nernst
D)Hodgkin
E)Katz

Question 36

Which of the following statements is false regarding the nicotinic acetylcholine receptor?

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 cobratoxin.
E)It is comprised of four large subunits.

Question 37

The stimulation of a neuron by a signal may ultimately stimulate

A)another nerve cell.
B)skeletal muscle cells.
C)gland cells.
D)smooth muscle cells.
E)all of the above

Question 38

The technique that allows one to record ion currents passing through individual channels is known as

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

Question 39

The somatic nervous system controls

A)the brain and spinal cord.
B)some glands.
C)skeletal muscles.
D)cardiac muscle.
E)smooth muscle.

Question 40

Which of the following statements about action potentials is false?

A)Electrical signals are propagated along a dendrite.
B)They require rapid changes in membrane potential.
C)Due to leaking, membranes are subject to subthreshold depolarization, which is insufficient to produce the action potential.
D)At the end of the action potential, most neurons show a transient hyperpolarization.
E)A refractory period is always necessary following an action potential.

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

For treatment of ADHD (attention deficit hyperactivity disorder),tricyclic antidepressants are often prescribed.These drugs act by affecting the reuptake of neurotransmitters.What effects does this have on the postsynaptic neuron? (Assume an excitatory neurotransmitter.)

Question 43

You have prepared lipid micelles that possess a leaky Na+ ion channel,and,for purposes of experimentation,the cytosolic sides of the channels are facing outward. Predict what will happen with the Na⁺ ion movement and the probable impact on the development of an action potential across the micelle membrane if (a)there were an equivalent amounts of Na⁺ ions on both sides of the membrane,(b)a greater Na⁺ ion concentration inside the micelle,and (c)a greater concentration of Na⁺ ions outside the micelle.

Question 44

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

Question 45

Acetylcholine receptors can be differentiated by their ability to be activated by substances such as ________ and ________.

Question 46

________ are responsible for the transmission of a signal between two adjacent nerve cells.

Question 47

The kinesin ATPase is located within the ________ of a nerve cell.

Question 48

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

Question 49

Many drugs work by interfering with the inactivation of neurotransmitters once they have been released.What are the two basic mechanisms whereby a drug may interfere in this process? Explain how you would design a potential mechanism for a new drug based on either of these mechanisms.

Question 50

Ions of ________ initiate the release of a neurotransmitter,such as acetylcholine,via ________ into the synaptic cleft.

Question 51

________ receptors act more slowly because they act in a(n)________ manner.

Question 52

Describe the docking and fusion of vesicles with the cell membrane.How do tetanus toxin and botulinum toxin work to interfere with this process?

Question 53

An ________ of a nerve cell is the temporary depolarization and repolarization of the cell membrane.

Question 54

Synaptic vesicles are synthesized in the nerve ________.

Question 55

________ is an autoimmune disease characterized by the presence of antibodies that are capable of binding acetylcholine receptors.

Question 56

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

Question 57

Visualize a neuromuscular junction.An impulse has been sent to the effectors (muscle cells)for a response.At rest,the endplate region has the following concentrations of sodium and potassium: [Na⁺in] = 10 mM,[Na⁺out] = 145 mM,[K⁺in] = 140 mM,and [K⁺out] = 5 mM.Remember that when acetylcholine binds to its receptors,a large opening of channels becomes permeable to both sodium and potassium.What is the membrane potential of the endplate region when stimulated by acetylcholine in this response?

Question 58

Upon transmission of a nerve signal to a muscle cell,________ is released from the sarcoplasmic reticulum through a gated channel.