Question 1

In myelinated fibers the action potential can be significantly slowed down by synaptic
 delays of as much as 1-2 msec.

Accepted Answer

A) True 
 B)False  False

Question 2

In the nervous system, the term membrane potential refers to the

Accepted Answer

A)  ability of a cell membrane to conduct an electrical impulse 
B)  separation of charges across a biological membrane. 
C)  ability of a membrane to give rise to vesicles. 
D)  ability of a cell membrane to transport Na+ and K+ ions 
E)  ability of the plasma membrane to form T-tubules. 
A)  ability of a cell membrane to conduct an electrical impulse 
B)  separation of charges across a biological membrane. 
C)  ability of a membrane to give rise to vesicles. 
D)  ability of a cell membrane to transport Na+ and K+ ions 
E)  ability of the plasma membrane to form T-tubules. B

Question 3

Which of the following statements about graded potentials and action potentials is NOT true?

Accepted Answer

A)  The duration of a graded potential is related to the duration of the stimulus. 
B)  Graded potentials can by produced by the net movement of Na+, Cl-, K+ or Ca+
Across the plasma membrane. 
C)  Graded potentials can occur as the result of either hyperpolarization of
Depolarization of the plasma membrane. 
D)  Action potentials show temporal and spatial summation. 
E)  Action potentials are triggered through the passive spread of membrane
Depolarization. 
A)  The duration of a graded potential is related to the duration of the stimulus. 
B)  Graded potentials can by produced by the net movement of Na+, Cl-, K+ or Ca+
Across the plasma membrane. 
C)  Graded potentials can occur as the result of either hyperpolarization of
Depolarization of the plasma membrane. 
D)  Action potentials show temporal and spatial summation. 
E)  Action potentials are triggered through the passive spread of membrane
Depolarization. D

Question 4

Which of the following characteristics are associated with graded potentials?

Accepted Answer

A)  They exhibit an "all-or-none" character. 
B)  Their magnitude is related to the intensity of the stimulus that elicits them. 
C)  They spread by active conductance. 
D)  They occur only in axons. 
A)  They exhibit an "all-or-none" character. 
B)  Their magnitude is related to the intensity of the stimulus that elicits them. 
C)  They spread by active conductance. 
D)  They occur only in axons.

Question 5

Match each sentence with the most appropriate choice:
-Hyperpolarization

Accepted Answer

A)  Calcium 
B)  Postsynaptic neuron 
C)  Gap junction 
D)  Dense-core vesicles 
E)  All-or-none
F) Reduced membrane potential
G) Increased membrane potential
H) Decremental
I) Salutatory conduction
J) Action potential frequency 
A)  Calcium 
B)  Postsynaptic neuron 
C)  Gap junction 
D)  Dense-core vesicles 
E)  All-or-none
F) Reduced membrane potential
G) Increased membrane potential
H) Decremental
I) Salutatory conduction
J) Action potential frequency

Question 6

If an electrical synapse conducted an action potential "backward" (from what would normally be the postsynaptic neuron to the presynaptic neuron), would an action potential be conducted in a retrograde direction (along the axon toward the cell body)?

Accepted Answer

A)  Yes. 
B)  No, since the normally presynaptic neuron lacks receptors for the ions carrying current from the normally postsynaptic neuron. 
C)  No, since the normally presynaptic neuron would be refractory to retrograde conduction. 
D)  No, unless the concentration gradients for all the relevant ions were reversed. 
E)  No, since there's no axon hillock at the axon terminal of the normally presynaptic neuron. 
A)  Yes. 
B)  No, since the normally presynaptic neuron lacks receptors for the ions carrying current from the normally postsynaptic neuron. 
C)  No, since the normally presynaptic neuron would be refractory to retrograde conduction. 
D)  No, unless the concentration gradients for all the relevant ions were reversed. 
E)  No, since there's no axon hillock at the axon terminal of the normally presynaptic neuron.

Question 7

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by increasing the membrane resistance of the axon?

Accepted Answer

A)  increasing the number of channels in the plasma membrane 
B)  myelinating the axon 
C)  increasing the diameter of the axon 
D)  placing all voltage-gated ion channels at distant intervals 
E)  decreasing the number of channels in the membrane. 
A)  increasing the number of channels in the plasma membrane 
B)  myelinating the axon 
C)  increasing the diameter of the axon 
D)  placing all voltage-gated ion channels at distant intervals 
E)  decreasing the number of channels in the membrane.

Question 8

Tetrodotoxin (TTX) is generally associated with pufferfish, which in fact gain it from symbiotic bacteria residing in them. Interestingly, the pufferfish themselves aren't affected by this neurotoxin. The most plausible explanation for the fish's insensitivity to TTX is

Accepted Answer

A)  the fish lack neurons. 
B)  the fish have neurons, but with very short axons that enable them to rely entirely on electrical conduction based on local passive current flow. 
C)  the fish lack voltage-gated sodium channels . 
D)  the fish have voltage-gated sodium channels, but they have a slightly different sequence from voltage-gated sodium channels found in other organisms, and this difference affects TTX's ability to bind the channel. 
A)  the fish lack neurons. 
B)  the fish have neurons, but with very short axons that enable them to rely entirely on electrical conduction based on local passive current flow. 
C)  the fish lack voltage-gated sodium channels . 
D)  the fish have voltage-gated sodium channels, but they have a slightly different sequence from voltage-gated sodium channels found in other organisms, and this difference affects TTX's ability to bind the channel.

Question 9

Local passive current flow decreases with distance because

Accepted Answer

A)  ion pumps which drive current flow run out of energy (ATP) as they drift from the stimulus site. 
B)  current leakage across the membrane attenuates current available for intracellular current flow. 
C)  as it gets away from the active zone, the membrane fluidity decreases and prevents influx of booster current. 
D)  of all of these reasons. 
E)  of none of these reasons. 
A)  ion pumps which drive current flow run out of energy (ATP) as they drift from the stimulus site. 
B)  current leakage across the membrane attenuates current available for intracellular current flow. 
C)  as it gets away from the active zone, the membrane fluidity decreases and prevents influx of booster current. 
D)  of all of these reasons. 
E)  of none of these reasons.

Question 10

Which of the following statements about the Na+ and K+ gradients in neurons is NOT true?

Accepted Answer

A)  In a resting neuron the electrical gradient for sodium is inward. 
B)  In a resting neuron the electrical gradient for potassium is inward. 
C)  In a resting neuron the concentration gradient for sodium is outward. 
D)  In a resting neuron the concentration gradient for potassium is outward. 
E)  In a resting neuron, the electrical and concentration gradients for sodium and
Potassium result in a membrane potential. 
A)  In a resting neuron the electrical gradient for sodium is inward. 
B)  In a resting neuron the electrical gradient for potassium is inward. 
C)  In a resting neuron the concentration gradient for sodium is outward. 
D)  In a resting neuron the concentration gradient for potassium is outward. 
E)  In a resting neuron, the electrical and concentration gradients for sodium and
Potassium result in a membrane potential.

Question 11

Which of the following is responsible for initiating changes in membrane potential resulting in an electrical signal?

Accepted Answer

A)  opening of voltage-gated ion channels 
B)  changes in membrane permeability in response to a stimulus 
C)  closing of voltage-gated ion channels 
D)  a change in the movement of ions through leak channels 
E)  closing of voltage-gated potassium channels 
A)  opening of voltage-gated ion channels 
B)  changes in membrane permeability in response to a stimulus 
C)  closing of voltage-gated ion channels 
D)  a change in the movement of ions through leak channels 
E)  closing of voltage-gated potassium channels

Question 12

Once threshold potential has been achieved, the permeability of the membrane to Na+ is

Accepted Answer

A)  greater than it was at rest. 
B)  greater than its permeability to K+. 
C)  increased due to activation of voltage-gated Na+ channels. 
D)  all of these. 
E)  none of these. 
A)  greater than it was at rest. 
B)  greater than its permeability to K+. 
C)  increased due to activation of voltage-gated Na+ channels. 
D)  all of these. 
E)  none of these.

Question 13

If they arrive simultaneously, as few as 30 EPSPs can bring a postsynaptic membrane to	threshold.

Accepted Answer

A) True 
 B)False

Question 14

Resting (membrane) potential is determined primarily by ____________ in the plasma membrane.

Accepted Answer

A)  leak channels. 
B)  voltage-gated channels. 
C)  ligand-gated channels. 
D)  stretch-activated channels. 
E)  phosphorylation-dependent channels. 
A)  leak channels. 
B)  voltage-gated channels. 
C)  ligand-gated channels. 
D)  stretch-activated channels. 
E)  phosphorylation-dependent channels.

Question 15

An investigator places an isolated neuron in a calcium-free medium. They give the neuron a suprathreshold stimulus and then perform an assay to test whether neurotransmitter is released into the medium. Which of the following outcomes would you predict?

Accepted Answer

A)  No neurotransmitter is detected since influx of calcium into the synaptic knob is required for neurotransmitter release. 
B)  No neurotransmitter is detected since influx of calcium is required in order for the neuron to conduct an action potential. 
C)  Neurotransmitter is detected since calcium is not required for action potential conduction and the initial stimulus was suprathreshold. 
D)  We cannot predict the outcome without knowing whether the neuron was myelinated. 
E)  None of these. 
A)  No neurotransmitter is detected since influx of calcium into the synaptic knob is required for neurotransmitter release. 
B)  No neurotransmitter is detected since influx of calcium is required in order for the neuron to conduct an action potential. 
C)  Neurotransmitter is detected since calcium is not required for action potential conduction and the initial stimulus was suprathreshold. 
D)  We cannot predict the outcome without knowing whether the neuron was myelinated. 
E)  None of these.

Question 16

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by decreasing the longitudinal resistance of the axon?

Accepted Answer

A)  increasing the number of channels in the plasma membrane 
B)  myelinating the axon 
C)  increasing the diameter of the axon 
D)  placing all voltage-gated ion channels at distant intervals 
E)  None of these. 
A)  increasing the number of channels in the plasma membrane 
B)  myelinating the axon 
C)  increasing the diameter of the axon 
D)  placing all voltage-gated ion channels at distant intervals 
E)  None of these.

Question 17

Fluoxetine (Prozac) is a serotonin re-uptake inhibitor. Serotonin is generally an excitatory neurotransmitter; therefore, one would expect using fluoxetine to result in ___________ in the post-synaptic neuron.

Accepted Answer

A)  action potentials of greater amplitude to be conducted 
B)  an increase in the conduction velocity of action potentials 
C)  graded potentials of lesser amplitude 
D)  graded potentials of shorter duration 
E)  graded potentials of longer duration 
A)  action potentials of greater amplitude to be conducted 
B)  an increase in the conduction velocity of action potentials 
C)  graded potentials of lesser amplitude 
D)  graded potentials of shorter duration 
E)  graded potentials of longer duration

Question 18

Due to their size, single cell organisms such as the Paramecium can rely on simple
 diffusion of signals to facilitate their movement.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following reasons explains why channels are required in membranes in order for neurons to perform their function?

Accepted Answer

A)  Neurons have to function in reception (e.g. sensory); therefore, they must be able to switch channels in order to get the appropriate information. 
B)  The lipid bilayer is impermeable to ions and polar molecules, and ion flow through the membrane is essential for nervous transmission of information. 
C)  Channels permit the flow of water through the membrane, and water is necessary for hydrolysis reactions in the cytoplasm. 
D)  Channels are required in order to keep Ca2+ levels low inside the cytoplasm. 
A)  Neurons have to function in reception (e.g. sensory); therefore, they must be able to switch channels in order to get the appropriate information. 
B)  The lipid bilayer is impermeable to ions and polar molecules, and ion flow through the membrane is essential for nervous transmission of information. 
C)  Channels permit the flow of water through the membrane, and water is necessary for hydrolysis reactions in the cytoplasm. 
D)  Channels are required in order to keep Ca2+ levels low inside the cytoplasm.

Question 20

If an excitatory synapse is activated at the same time as an inhibitory synapse, the effect on postsynaptic membrane potential will be

Accepted Answer

A)  no change. 
B)  a net depolarization since excitation normally triumphs over inhibition. 
C)  a net hyperpolarization since inhibition normally overwhelms excitation. 
D)  impossible to predict since we don't know the relative strength of these synapses. 
A)  no change. 
B)  a net depolarization since excitation normally triumphs over inhibition. 
C)  a net hyperpolarization since inhibition normally overwhelms excitation. 
D)  impossible to predict since we don't know the relative strength of these synapses.

In myelinated fibers the action potential can be significantly slowed down by synaptic delays of as much as 1-2 msec.

In the nervous system, the term membrane potential refers to the

Which of the following statements about graded potentials and action potentials is NOT true?

Which of the following characteristics are associated with graded potentials?

Match each sentence with the most appropriate choice: -Hyperpolarization

If an electrical synapse conducted an action potential "backward" (from what would normally be the postsynaptic neuron to the presynaptic neuron), would an action potential be conducted in a retrograde direction (along the axon toward the cell body)?

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by increasing the membrane resistance of the axon?

Tetrodotoxin (TTX) is generally associated with pufferfish, which in fact gain it from symbiotic bacteria residing in them. Interestingly, the pufferfish themselves aren't affected by this neurotoxin. The most plausible explanation for the fish's insensitivity to TTX is

Local passive current flow decreases with distance because

Which of the following statements about the Na⁺ and K⁺ gradients in neurons is NOT true?

Which of the following is responsible for initiating changes in membrane potential resulting in an electrical signal?

Once threshold potential has been achieved, the permeability of the membrane to Na⁺ is

If they arrive simultaneously, as few as 30 EPSPs can bring a postsynaptic membrane to threshold.

Resting (membrane) potential is determined primarily by ____________ in the plasma membrane.

An investigator places an isolated neuron in a calcium-free medium. They give the neuron a suprathreshold stimulus and then perform an assay to test whether neurotransmitter is released into the medium. Which of the following outcomes would you predict?

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by decreasing the longitudinal resistance of the axon?

Fluoxetine (Prozac) is a serotonin re-uptake inhibitor. Serotonin is generally an excitatory neurotransmitter; therefore, one would expect using fluoxetine to result in ___________ in the post-synaptic neuron.

Due to their size, single cell organisms such as the Paramecium can rely on simple diffusion of signals to facilitate their movement.

Which of the following reasons explains why channels are required in membranes in order for neurons to perform their function?

If an excitatory synapse is activated at the same time as an inhibitory synapse, the effect on postsynaptic membrane potential will be

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Nervous Systems

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Exam 4: Neuronal Physiology

In myelinated fibers the action potential can be significantly slowed down by synaptic delays of as much as 1-2 msec.

In the nervous system, the term membrane potential refers to the

Which of the following statements about graded potentials and action potentials is NOT true?

Which of the following characteristics are associated with graded potentials?

Match each sentence with the most appropriate choice: -Hyperpolarization

If an electrical synapse conducted an action potential "backward" (from what would normally be the postsynaptic neuron to the presynaptic neuron), would an action potential be conducted in a retrograde direction (along the axon toward the cell body)?

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by increasing the membrane resistance of the axon?

Tetrodotoxin (TTX) is generally associated with pufferfish, which in fact gain it from symbiotic bacteria residing in them. Interestingly, the pufferfish themselves aren't affected by this neurotoxin. The most plausible explanation for the fish's insensitivity to TTX is

Local passive current flow decreases with distance because

Which of the following statements about the Na+ and K+ gradients in neurons is NOT true?

Which of the following is responsible for initiating changes in membrane potential resulting in an electrical signal?

Once threshold potential has been achieved, the permeability of the membrane to Na+ is

If they arrive simultaneously, as few as 30 EPSPs can bring a postsynaptic membrane to threshold.

Resting (membrane) potential is determined primarily by ____________ in the plasma membrane.

An investigator places an isolated neuron in a calcium-free medium. They give the neuron a suprathreshold stimulus and then perform an assay to test whether neurotransmitter is released into the medium. Which of the following outcomes would you predict?

Which of the following evolutionary adaptations would result in an increase in the speed of conduction of action potentials by decreasing the longitudinal resistance of the axon?

Fluoxetine (Prozac) is a serotonin re-uptake inhibitor. Serotonin is generally an excitatory neurotransmitter; therefore, one would expect using fluoxetine to result in ___________ in the post-synaptic neuron.

Due to their size, single cell organisms such as the Paramecium can rely on simple diffusion of signals to facilitate their movement.

Which of the following reasons explains why channels are required in membranes in order for neurons to perform their function?

If an excitatory synapse is activated at the same time as an inhibitory synapse, the effect on postsynaptic membrane potential will be

Homeostasis and Integration: The Foundations of Physiology

Cellular and Molecular Physiology

Membrane Physiology

Nervous Systems

Sensory Physiology

Endocrine Systems

Muscle Physiology

Circulatory Systems

Defense Systems

Respiratory Systems

Excretory Systems

Fluid and Acid-Base Balance

Digestive Systems

Energy Balance and Thermal Physiology

Reproductive Systems

Filters

Which of the following statements about the Na⁺ and K⁺ gradients in neurons is NOT true?

Once threshold potential has been achieved, the permeability of the membrane to Na⁺ is