Question 1

Which nervous pathway does sensory information travel through to elicit a response in the effector cells?

Accepted Answer

A) CNS afferent division CNS interneuron PNS efferent division effector 
B) PNS efferent division CNS interneuron PNS afferent division effector 
C) CNS efferent division CNS interneuron PNS afferent division effector 
D) PNS afferent division CNS interneuron PNS efferent division effector 
A) CNS afferent division CNS interneuron PNS efferent division effector 
B) PNS efferent division CNS interneuron PNS afferent division effector 
C) CNS efferent division CNS interneuron PNS afferent division effector 
D) PNS afferent division CNS interneuron PNS efferent division effector D

Question 2

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?

Accepted Answer

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 
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 B

Question 3

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

Accepted Answer

A) increased heartbeat 
B) constriction of airways 
C) dilation of pupils 
D) all of the above 
E) only A and C 
A) increased heartbeat 
B) constriction of airways 
C) dilation of pupils 
D) all of the above 
E) only A and C E

Question 4

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

Accepted Answer

A) true 
B) false 
A) true 
B) false

Question 5

Action potentials are normally generated at the axon hillock and propagated down the axon away from the cell body.If you experimentally depolarized an axon to the threshold level at a point halfway down the axon,what would happen?

Accepted Answer

A) An action potential would be generated that would travel to the synapse with the next neuron. 
B) An action potential would be generated that would travel back towards the cell body. 
C) No action potential could be generated at this location. 
D) Answers A and B both apply. 
A) An action potential would be generated that would travel to the synapse with the next neuron. 
B) An action potential would be generated that would travel back towards the cell body. 
C) No action potential could be generated at this location. 
D) Answers A and B both apply.

Question 6

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

Accepted Answer

A) K⁺ 
B) Na⁺ 
C) Ca⁺⁺ 
D) Cl⁻ 
E) Mg⁺⁺ 
A) K⁺ 
B) Na⁺ 
C) Ca⁺⁺ 
D) Cl⁻ 
E) Mg⁺⁺

Question 7

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

Accepted Answer

A) interneuron 
B) motor neuron 
C) sensory neuron 
D) A and B 
E) all of the above 
A) interneuron 
B) motor neuron 
C) sensory neuron 
D) A and B 
E) all of the above

Question 8

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?

Accepted Answer

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. 
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 9

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?

Accepted Answer

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) Answers A and B are both correct. 
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) Answers A and B are both correct.

Question 10

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

Accepted Answer

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

Question 11

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

Accepted Answer

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. 
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 12

Where are the sodium channels that trigger an action potential located?

Accepted Answer

A) axon hillock 
B) axon dendrite 
C) axon terminal 
D) axon cell body 
A) axon hillock 
B) axon dendrite 
C) axon terminal 
D) axon cell body

Question 13

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

Accepted Answer

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. 
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 14

The autonomic nervous system does NOT control

Accepted Answer

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

Question 15

Motor neurons release the neurotransmitter acetylcholine (Ach).What would you expect to happen if the acetylcholine is released in high concentrations and is not properly degraded after it binds the receptor on the postsynaptic membrane?

Accepted Answer

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 
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 16

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

Accepted Answer

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

Question 17

If the sodium-potassium pump were inactivated by a drug,what would happen to the neuron's membrane potential?

Accepted Answer

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

Question 18

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

Accepted Answer

A) true 
B) false 
A) true 
B) false

Question 19

Neurotransmitters can be either excitatory or inhibitory.Which of the following neurotransmitters usually have an inhibitory effect on the post-synaptic cell?

Accepted Answer

A) acetylcholine 
B) gamma-aminobutyric acid 
C) glutamate 
D) dopamine 
A) acetylcholine 
B) gamma-aminobutyric acid 
C) glutamate 
D) dopamine

Question 20

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

Accepted Answer

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) both A and B 
E) both A and C 
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) both A and B 
E) both A and C

Exam 45: Electrical Signals in Animals

Which nervous pathway does sensory information travel through to elicit a response in the effector cells?

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?

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

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

Action potentials are normally generated at the axon hillock and propagated down the axon away from the cell body.If you experimentally depolarized an axon to the threshold level at a point halfway down the axon,what would happen?

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

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

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 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?

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

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

Where are the sodium channels that trigger an action potential located?

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

The autonomic nervous system does NOT control

Motor neurons release the neurotransmitter acetylcholine (Ach).What would you expect to happen if the acetylcholine is released in high concentrations and is not properly degraded after it binds the receptor on the postsynaptic membrane?

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

If the sodium-potassium pump were inactivated by a drug,what would happen to the neuron's membrane potential?

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

Neurotransmitters can be either excitatory or inhibitory.Which of the following neurotransmitters usually have an inhibitory effect on the post-synaptic cell?

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

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, membranes, and the First Cells

Inside the Cell

Cell-Cell Interactions

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, RNA Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

Analyzing and Engineering Genes

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Principles of Development

An Introduction to Animal Development

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Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

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Protists

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An Introduction to Animals

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Water and Sugar Transport in Plants

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Plant Sensory Systems, signals, and Responses

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Water and Electrolyte Balance in Animals

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Gas Exchange and Circulation

Animal Sensory Systems and Movement

Chemical Signals in Animals

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