Deck 45: Electrical Signals in Animals

Question 1

If the activity of the sodium-potassium pump were changed by palytoxin (a toxin derived from coral)what would happen to the neuron's membrane potential?

A)immediate loss of resting potential
B)immediate loss of action potentials
C)slow decrease of resting potential
D)no effect

Answer 1

C

Question 2

Figure 45.1

Which letter on Figure 45.1 corresponds to a large influx of Na⁺ ions into the cell?

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

Answer 2

B

Question 3

Which of the following statements about action potentials is false?

A)All action potentials for a given neuron are identical in magnitude.
B)All action potentials for a given neuron are identical in duration.
C)Action potentials are propagated down the length of the axon.
D)Movement of ions during the action potential occurs mostly through the sodium pump.
E)The frequency of action potentials,not their size,is the meaningful signal.

Answer 3

D

Question 4

What type of neuron can exist entirely within the central nervous system (CNS)?

A)interneuron
B)motor neuron
C)sensory neuron
D)interneuron and motor neuron
E)interneuron,sensory neuron,and motor neuron

Question 5

If a doctor attempts to trigger the patellar tendon reflex and a lack of response occurs,what are potential regions where pathology might exist?

A)the brain
B)the knee
C)the spinal cord
D)the knee and spinal cord
E)the knee and the brain

Question 6

If you experimentally increase the concentration of Na⁺ outside a cell while maintaining other ion concentrations as they were,what would happen to the cell's membrane potential?

A)The membrane potential would decrease.
B)The membrane potential would increase.
C)The membrane potential would be unaffected.
D)The answer depends on the thermodynamic potential.

Question 7

A neurophysiologist is investigating nerve reflexes in two different animals a crab and a fish.Action potentials are found to pass more rapidly along the fish's neurons.What is the most likely explanation?

A)The fish's axons are smaller in diameter;small axons transmit action potentials faster than large axons do.
B)Unlike the crab,the fish's axons are wrapped in myelin.
C)There are more ion channels in the axons of the crab compared with fish axons.
D)Unlike the crab,the fish's axons are wrapped in myelin,and the fish's axons are smaller in diameter;small axons transmit action potentials faster than large axons do.

Question 8

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

A)because the Na⁺ concentration is much higher outside the cell than it is inside
B)because the Na⁺ ions are attracted to the negatively charged interior
C)because the Na⁺ ions are actively transported by the sodium-potassium pump into the cell
D)because the Na⁺ concentration is much higher outside the cell than it is inside,and the Na⁺ ions are attracted to the negatively charged interior
E)because the Na⁺ concentration is much higher outside the cell than it is inside,and the Na⁺ ions are actively transported by the sodium-potassium pump into the cell

Question 9

Why do the action potentials of some axons move more quickly than those of other axons?

A)larger diameter
B)Drugs that affect the activity of neurotransmitters
C)the presence of a myelin sheath
D)all of the above
E)none of the above

Question 10

Figure 45.1

Which letter in Figure 45.1 corresponds to a large efflux of K⁺ ions from the cell?

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

Question 11

Figure 45.1

Which letter on Figure 45.1 corresponds to the action of the sodium-potassium pump and potassium leak channels?

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

Question 12

The axons of most neurons contain just one type of sodium channel,but several types of potassium channels.

Question 13

What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?

A)The action potential would be propagated nearly instantaneously to the synapse.
B)There could be no action potential generated at the axon hillock.
C)The signal would fade because it is not renewed by the opening of more sodium channels.
D)None of the above could happen.

Question 14

The Nernst equation specifies the equilibrium potential for a particular ion.This equilibrium potential is a function of _____.

A)hydrostatic pressure
B)ion concentration gradient
C)osmotic gradient
D)temperature (thermal)gradient
E)the ion concentration gradient and the temperature (thermal)gradient

Question 15

Tetrodotoxin blocks voltage-gated sodium channels and ouabain blocks sodium-potassium pumps.If you added both tetrodotoxin and ouabain to a solution containing neural tissue,what responses would you expect?

A)immediate loss of resting potential
B)immediate loss of action potential with gradual loss of resting potential
C)slow decrease of resting potential and action potential amplitudes
D)no effect;the substances counteract each other

Question 16

Which of the following ions is most likely to cross the plasma membrane of a resting neuron?

A)K⁺
B)Na⁺
C)Ca²⁺
D)Cl⁻
E)Mg²⁺

Question 17

How do myelin sheaths increase the speed with which action potentials are propagated along an axon?

A)They increase the permeability of Na⁺ ions in the plasma membrane.
B)They amplify the action potential by increasing sodium influx along the entire distance of the neuron.
C)They cause action potentials to "jump" down the axon rather than travel in a continuous path along every site on the axon.
D)All of the above answers apply.

Question 18

The depolarization phase of an action potential requires _____.

A)opening of K⁺ channels in the membrane
B)opening of Na⁺ channels in the membrane
C)opening of Ca²⁺ channels in the membrane
D)a K⁺ concentration gradient across the membrane
E)a Ca²⁺ concentration gradient across the membrane

Question 19

The concentrations of ions are very different inside and outside a nerve cell due to _____.

A)osmosis
B)diffusion
C)sodium-potassium pumps
D)symports and antiports

Question 20

If you experimentally increase the concentration of K⁺ inside a cell while maintaining other ion concentrations as they were,what would happen to the cell's membrane potential?

A)The membrane potential would become more negative.
B)The membrane potential would become less negative.
C)The membrane potential would remain the same.

Question 21

Motor neurons release the neurotransmitter acetylcholine (ACh)and acetylcholinesterase degrades ACh in the synapse.If a neurophysiologist applies onchidal (a naturally occurring acetylcholinesterase inhibitor produced by the mollusk Onchidella binneyi)to a synapse,what would you expect to happen?

A)paralysis of muscle tissue
B)gradual loss of resting potential
C)convulsions due to constant muscle stimulation
D)decrease in the frequency of action potentials
E)no effect

Question 22

A large meal is likely to result in activity in which set of nerves?

A)parasympathetic nerves
B)somatic nerves
C)sympathetic nerves
D)both the somatic and sympathetic nerves

Question 23

One of the complications of Alzheimer's is an interference with learning and memory.An effect of this disease should involve _____.

A)changes in the concentration of ions in the extracellular fluid surrounding neurons
B)changes in myelination of axons
C)changes to the chemical structure of neurotransmitters
D)molecular and structural changes at synapses
E)structural changes to ion channels in axons

Question 24

Patients with dysautonomia (autonomic nervous system disorders)will show symptoms in all of the following except _____.

A)airway diameter
B)contraction of skeletal muscles
C)heart rate
D)pupil dilation and constriction
E)stomach activity

Question 25

Stem cell transplants may someday be used to treat Parkinson's disease.Researchers are hopeful that these cells would alleviate the symptoms of Parkinson's disease by _____.

A)preventing temporal lobe seizures
B)repairing sites of traumatic brain injury
C)replenishing missing ion channels
D)secreting the neurotransmitter dopamine
E)preventing temporal lobe seizures and secreting the neurotransmitter dopamine

Question 26

If a patient has an injury in the brain stem,which of the following would be observed?

A)auditory hallucinations
B)visual hallucinations
C)an inability to regulate body temperature
D)an inability to regulate heart function

Question 27

If twice as many inhibitory postsynaptic potentials (IPSPs)as excitatory postsynaptic potentials (EPSPs)arrive at a postsynaptic neuron in close proximity,is the integration of signals by the postsynaptic neuron likely to produce an action potential?

A)Yes
B)No

Question 28

In multiple sclerosis the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results.How does this disease manifest at the level of the action potential?

A)Action potentials move in the opposite direction on the axon.
B)Action potentials move more slowly along the axon.
C)Action potentials are entirely negated.
D)All of the above occurs in multiple sclerosis.

Question 29

How could you increase the magnitude of inhibitory postsynaptic potentials (IPSPs)generated at a synapse?

A)increase sodium-potassium pump activity
B)increase K⁺ permeability
C)increase the influx of calcium
D)All of the above apply.

Question 30

Neurotransmitter is released _____.

A)in response to an action potential depolarizing the presynaptic membrane
B)when threshold potential is reached
C)when enough voltage-gated sodium channels open

Question 31

Which of the following manipulations would reduce the release of neurotransmitter from a presynaptic neuron terminal?

A)reduction in extracellular calcium ion concentration at the axon terminal
B)increase in extracellular sodium and potassium ion concentrations at the axon terminal
C)addition of tetrodotoxin to the extracellular fluid at the axon terminal
D)All of the above manipulations would reduce the release of neurotransmitter.

Question 32

Most synapses found so far in the mammalian central nervous system (CNS)are classified as chemical rather than electrical.

Question 33

Upon witnessing a robber hold up a convenience store at gunpoint,which of the following reactions would your nervous system initiate?

A)increased heartbeat
B)constriction of airways
C)constriction of pupils
D)decreased heartbeat