Question 1

During which of the following states are the majority of voltage -gated sodium channels closed and incapable of opening?

Accepted Answer

A)   during the absolute refractory period
B)   during the after -hyperpolarization
C)   during depolarization
D)   during the relative refractory period
E)   at the resting membrane potential

Question 2

Both activation and inactivation gates of a sodium channel are stimulated at the same time by a depolarization with the inactivation gate acting more slowly than the activation gate, thereby allowing sodium to enter the cell.

Accepted Answer

A) True 
 B)False

Question 3

-Identify the type of summation that is occurring in Figure 7.1 where "S" refers to a stimulus from one source measured in the postsynaptic membrane.

Accepted Answer

A)   spatial
B)   multiplier
C)   temporal
D)   suprathreshold
E)   subthreshold

Question 4

Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects the efferent division, particularly the motor neurons, of the nervous system. People with ALS have normal bodily functions and their ability to think, form memories, and to detect sensations is all normal. However, the progressive nature of this disease can lead to total paralysis. Based on your knowledge of the different divisions of the nervous system and the functioning of neurons, explain the symptoms of ALS.

Accepted Answer

The efferent division of the nervous sys...

Question 5

If the soma of a neuron became more permeable to potassium, which statement below best describes the graded potential that would be generated in the soma?

Accepted Answer

A)   Potassium would leave the cell, causing the membrane to hyperpolarize.
B)   Potassium is a cation; therefore, it would cause an excitatory depolarization.
C)   Potassium is an inhibitory second messenger; therefore, it would cause amplification of the graded potential.
D)   Potassium would reach its equilibrium potential and the voltage inside the cell would not change.
E)   Potassium would enter the cell, causing the membrane to depolarize and reach threshold.

Question 6

During the rapid depolarization phase of an action potential, the plasma membrane is more permeable to which of the following ions?

Accepted Answer

A)   sodium (Na+) 
B)   potassium (K+) 
C)   chloride (Cl -) 
D)   calcium (Ca++) 
E)   phosphate (PO4 -)

Question 7

Saxitoxin (STX)  is the most well -known paralytic shellfish toxin caused by the phenomenon known as "red tide." Which statement below best describes why this neurotoxin causes paralysis?

Accepted Answer

A)   It acts by blocking voltage -gated sodium channels which are needed to generate an action potential.
B)   It acts on the hypothalamus of the brain, shutting down all neurological functions.
C)   It prevents the synaptic vesicles from migrating to the axon terminal; therefore, no action potentials are generated.
D)   It blocks ligand -gated channels on the postsynaptic membrane, which blocks signals leaving the central nervous system.
E)   It acts on the potassium channels within a neuron, hyperpolarizing the cell membrane; therefore, no action potential can be generated.

Question 8

_________is the mechanism by which action potentials are propagated in unmyelinated axons.

Accepted Answer

A)   The regenerative mechanism
B)   The all -or -none principle
C)   Temporal summation
D)   Electrotonic conduction
E)   After -hyperpolarization

Question 9

Excitatory graded potentials are those where the stimulus initiates a hyperpolarization of the cell.

Accepted Answer

A) True 
 B)False

Question 10

What is the inverse of resistance?

Accepted Answer

A)   flux
B)   current
C)   conductance
D)   voltage
E)   impedance

Question 11

What is the most common neuronal cell type?

Accepted Answer

A)   efferent neuron
B)   pseudo -unipolar neuron
C)   afferent neuron
D)   bipolar neuron
E)   interneuron

Question 12

Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials?

Accepted Answer

A)   The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the repolarization phase.
B)   The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the after -hyperpolarization.
C)   The movement of sodium and potassium ions that occurs during an action potential is countered by counter -transport of potassium with sodium during rest.
D)   The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump.
E)   The movement of sodium and potassium ions that occurs during an action potential is countered by the passive leak of these ions when a neuron is at rest.

Question 13

Which type of glial cell provides the myelin sheath for many axons in the central nervous system?

Accepted Answer

A)   astrocytes
B)   oligodendrocytes
C)   microglia
D)   ependymal cells
E)   Schwann cell

Question 14

The resting membrane potential is close to the equilibrium potential of which of the following ions?

Accepted Answer

A)   sodium (Na+) 
B)   potassium (K+) 
C)   chloride (Cl -) 
D)   calcium (Ca++) 
E)   phosphate (PO4 -)

Question 15

What nervous system is found in the intestinal tract?

Accepted Answer

A)   afferent nervous system
B)   somatic nervous system
C)   efferent nervous system
D)   enteric nervous system
E)   central nervous system

Question 16

Which of the following potentials dissipate in size as the potential moves away from the site of initiation?

Accepted Answer

A)   graded potentials
B)   threshold potentials
C)   action potentials
D)   both graded potentials and action potentials
E)   neither graded potentials nor action potentials

Question 17

Describe how an action potential, originating at the axon hillock, is propagated along the axon. Include those factors that can alter conduction velocity.

Accepted Answer

As an action potential is generated at t...

Question 18

At the resting membrane potential, the membrane is most permeable to________ , which moves_______the cell due to its electrochemical gradient.

Accepted Answer

A)   chloride : into
B)   potassium : into
C)   sodium : out of
D)   sodium : into
E)   potassium : out of

Question 19

The membrane potential of a cell is determined exclusively by that cell's sodium and potassium permeability.

Accepted Answer

A) True 
 B)False

Question 20

The Na+/K+ pump distributes three sodium ions to the outside of the membrane and two potassium ions to the inside of the membrane.

Accepted Answer

A) True 
 B)False

Exam 7: Nerve Cells and Electrical Signaling

The membrane potential of a cell is determined exclusively by that cell's sodium and potassium permeability.

Correct Answer
verified

Excitatory graded potentials are those where the stimulus initiates a hyperpolarization of the cell.

Correct Answer
verified

Saxitoxin (STX) is the most well -known paralytic shellfish toxin caused by the phenomenon known as "red tide." Which statement below best describes why this neurotoxin causes paralysis?

Correct Answer
verified

Both activation and inactivation gates of a sodium channel are stimulated at the same time by a depolarization with the inactivation gate acting more slowly than the activation gate, thereby allowing sodium to enter the cell.

Correct Answer
verified

At the resting membrane potential, the membrane is most permeable to__ , which moves_the cell due to its electrochemical gradient.

Correct Answer
verified

-Identify the type of summation that is occurring in Figure 7.1 where "S" refers to a stimulus from one source measured in the postsynaptic membrane.

Correct Answer
verified

What nervous system is found in the intestinal tract?

Correct Answer
verified

Which of the following potentials dissipate in size as the potential moves away from the site of initiation?

Correct Answer
verified

If the soma of a neuron became more permeable to potassium, which statement below best describes the graded potential that would be generated in the soma?

Correct Answer
verified

What is the most common neuronal cell type?

Correct Answer
verified

During the rapid depolarization phase of an action potential, the plasma membrane is more permeable to which of the following ions?

Correct Answer
verified

Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials?

Correct Answer
verified

The resting membrane potential is close to the equilibrium potential of which of the following ions?

Correct Answer
verified

Which type of glial cell provides the myelin sheath for many axons in the central nervous system?

Correct Answer
verified

During which of the following states are the majority of voltage -gated sodium channels closed and incapable of opening?

Correct Answer
verified

The Na⁺/K⁺pump distributes three sodium ions to the outside of the membrane and two potassium ions to the inside of the membrane.

Correct Answer
verified

What is the inverse of resistance?

Correct Answer
verified

Describe how an action potential, originating at the axon hillock, is propagated along the axon. Include those factors that can alter conduction velocity.

Correct Answer
verified
As an action potential is generated at t...
View Answer

_________is the mechanism by which action potentials are propagated in unmyelinated axons.

Correct Answer
verified

Correct Answer
verified
The efferent division of the nervous sys...
View Answer

Exam 7: Nerve Cells and Electrical Signaling

The membrane potential of a cell is determined exclusively by that cell's sodium and potassium permeability.

Correct AnswerverifiedShow Answer

Excitatory graded potentials are those where the stimulus initiates a hyperpolarization of the cell.

Correct AnswerverifiedShow Answer

Saxitoxin (STX) is the most well -known paralytic shellfish toxin caused by the phenomenon known as "red tide." Which statement below best describes why this neurotoxin causes paralysis?

Correct AnswerverifiedShow Answer

Both activation and inactivation gates of a sodium channel are stimulated at the same time by a depolarization with the inactivation gate acting more slowly than the activation gate, thereby allowing sodium to enter the cell.

Correct AnswerverifiedShow Answer

At the resting membrane potential, the membrane is most permeable to________ , which moves_______the cell due to its electrochemical gradient.

Correct AnswerverifiedShow Answer

-Identify the type of summation that is occurring in Figure 7.1 where "S" refers to a stimulus from one source measured in the postsynaptic membrane.

Correct AnswerverifiedShow Answer

What nervous system is found in the intestinal tract?

Correct AnswerverifiedShow Answer

Which of the following potentials dissipate in size as the potential moves away from the site of initiation?

Correct AnswerverifiedShow Answer

If the soma of a neuron became more permeable to potassium, which statement below best describes the graded potential that would be generated in the soma?

Correct AnswerverifiedShow Answer

What is the most common neuronal cell type?

Correct AnswerverifiedShow Answer

During the rapid depolarization phase of an action potential, the plasma membrane is more permeable to which of the following ions?

Correct AnswerverifiedShow Answer

Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials?

Correct AnswerverifiedShow Answer

The resting membrane potential is close to the equilibrium potential of which of the following ions?

Correct AnswerverifiedShow Answer

Which type of glial cell provides the myelin sheath for many axons in the central nervous system?

Correct AnswerverifiedShow Answer

During which of the following states are the majority of voltage -gated sodium channels closed and incapable of opening?

Correct AnswerverifiedShow Answer

The Na+/K+ pump distributes three sodium ions to the outside of the membrane and two potassium ions to the inside of the membrane.

Correct AnswerverifiedShow Answer

What is the inverse of resistance?

Correct AnswerverifiedShow Answer

Describe how an action potential, originating at the axon hillock, is propagated along the axon. Include those factors that can alter conduction velocity.

Correct AnswerverifiedAs an action potential is generated at t...View AnswerShow Answer

_________is the mechanism by which action potentials are propagated in unmyelinated axons.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThe efferent division of the nervous sys...View AnswerShow Answer

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
verified

At the resting membrane potential, the membrane is most permeable to__ , which moves_the cell due to its electrochemical gradient.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The Na⁺/K⁺pump distributes three sodium ions to the outside of the membrane and two potassium ions to the inside of the membrane.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
As an action potential is generated at t...
View Answer

Correct Answer
verified

Correct Answer
verified
The efferent division of the nervous sys...
View Answer