Question 1

The "threshold" potential of a membrane

Accepted Answer

A)  is the point of separation from a living to a dead neuron. 
B)  is the lowest frequency of action potentials a neuron can produce. 
C)  is the minimum hyperpolarization needed to prevent the occurrence of action potentials. 
D)  is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels. 
E)  is the peak amount of depolarization seen in an action potential. 
A)  is the point of separation from a living to a dead neuron. 
B)  is the lowest frequency of action potentials a neuron can produce. 
C)  is the minimum hyperpolarization needed to prevent the occurrence of action potentials. 
D)  is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels. 
E)  is the peak amount of depolarization seen in an action potential.

Question 2

For the following questions, refer to the graph of an action potential.
  
-The minimum graded depolarization needed to operate the voltage-gated sodium and potassium channels is indicated by the label

Accepted Answer

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

Question 3

Temporal summation always involves

Accepted Answer

A)  both inhibitory and excitatory inputs. 
B)  synapses at more than one site. 
C)  inputs that are not simultaneous. 
D)  electrical synapses. 
E)  multiple inputs at a single synapse. 
A)  both inhibitory and excitatory inputs. 
B)  synapses at more than one site. 
C)  inputs that are not simultaneous. 
D)  electrical synapses. 
E)  multiple inputs at a single synapse.

Question 4

The "selectivity" of a particular ion channel refers to its

Accepted Answer

A)  permitting passage by positive but not negative ions. 
B)  permitting passage by negative but not positive ions. 
C)  ability to change its size depending on the ion needing transport. 
D)  binding with only one type of neurotransmitter. 
E)  permitting passage only to a specific ion. 
A)  permitting passage by positive but not negative ions. 
B)  permitting passage by negative but not positive ions. 
C)  ability to change its size depending on the ion needing transport. 
D)  binding with only one type of neurotransmitter. 
E)  permitting passage only to a specific ion.

Question 5

In a simple synapse, neurotransmitter chemicals are released by

Accepted Answer

A)  the dendritic membrane. 
B)  the presynaptic membrane. 
C)  axon hillocks. 
D)  cell bodies. 
E)  ducts on the smooth endoplasmic reticulum. 
A)  the dendritic membrane. 
B)  the presynaptic membrane. 
C)  axon hillocks. 
D)  cell bodies. 
E)  ducts on the smooth endoplasmic reticulum.

Question 6

A "resting" motor neuron is expected to

Accepted Answer

A)  release lots of acetylcholine. 
B)  have high permeability to sodium ions. 
C)  be equally permeable to sodium and potassium ions. 
D)  exhibit a resting potential that is more negative than the "threshold" potential. 
E)  have a higher concentration of sodium ions on the inside of the cell than on the outside. 
A)  release lots of acetylcholine. 
B)  have high permeability to sodium ions. 
C)  be equally permeable to sodium and potassium ions. 
D)  exhibit a resting potential that is more negative than the "threshold" potential. 
E)  have a higher concentration of sodium ions on the inside of the cell than on the outside.

Question 7

The "undershoot" phase of after-hyperpolarization is due to

Accepted Answer

A)  slow opening of voltage-gated sodium channels. 
B)  sustained opening of voltage-gated potassium channels. 
C)  rapid opening of voltage-gated calcium channels. 
D)  slow restorative actions of the sodium-potassium ATPase. 
E)  ions that move away from their open ion channels. 
A)  slow opening of voltage-gated sodium channels. 
B)  sustained opening of voltage-gated potassium channels. 
C)  rapid opening of voltage-gated calcium channels. 
D)  slow restorative actions of the sodium-potassium ATPase. 
E)  ions that move away from their open ion channels.

Question 8

ATP hydrolysis directly powers the movement of

Accepted Answer

A)  K⁺ out of cells. 
B)  Na⁺ out of cells. 
C)  Na⁺ into cells. 
D)  Ca⁺⁺ into cells. 
E)  Cl⁻ into cells. 
A)  K⁺ out of cells. 
B)  Na⁺ out of cells. 
C)  Na⁺ into cells. 
D)  Ca⁺⁺ into cells. 
E)  Cl⁻ into cells.

Question 9

Adjacent neurons with direct (non-neurotransmitter)action potential transfer are said to have electrical synapses, based on the presence of

Accepted Answer

A)  tight junctions at their point of contact. 
B)  gap junctions at their point of contact. 
C)  leaky junctions at their point of contact. 
D)  anchoring junctions at their point of contact. 
E)  desmosomes at their point of contact. 
A)  tight junctions at their point of contact. 
B)  gap junctions at their point of contact. 
C)  leaky junctions at their point of contact. 
D)  anchoring junctions at their point of contact. 
E)  desmosomes at their point of contact.

Question 10

Neurotransmitters affect postsynaptic cells by

Accepted Answer

A)  initiating signal transduction pathways in the cells. 
B)  causing molecular changes in the cells. 
C)  affecting ion-channel proteins. 
D)  altering the permeability of the cells. 
E)  All of these options are correct. 
A)  initiating signal transduction pathways in the cells. 
B)  causing molecular changes in the cells. 
C)  affecting ion-channel proteins. 
D)  altering the permeability of the cells. 
E)  All of these options are correct.

Question 11

A simple nervous system

Accepted Answer

A)  must include chemical senses, mechanoreception, and vision. 
B)  includes a minimum of 12 effector neurons. 
C)  has information flow in only one direction: toward an integrating center. 
D)  has information flow in only one direction: away from an integrating center. 
E)  includes sensory information, an integrating center, and effectors. 
A)  must include chemical senses, mechanoreception, and vision. 
B)  includes a minimum of 12 effector neurons. 
C)  has information flow in only one direction: toward an integrating center. 
D)  has information flow in only one direction: away from an integrating center. 
E)  includes sensory information, an integrating center, and effectors.

Question 12

A graded hyperpolarization of a membrane can be induced by

Accepted Answer

A)  increasing its membrane's permeability to Na⁺. 
B)  decreasing its membrane's permeability to H⁺. 
C)  decreasing its membrane's permeability to Cl⁻. 
D)  increasing its membrane's permeability to Ca⁺⁺. 
E)  increasing its membrane's permeability to K⁺. 
A)  increasing its membrane's permeability to Na⁺. 
B)  decreasing its membrane's permeability to H⁺. 
C)  decreasing its membrane's permeability to Cl⁻. 
D)  increasing its membrane's permeability to Ca⁺⁺. 
E)  increasing its membrane's permeability to K⁺.

Question 13

When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of

Accepted Answer

A)  temporal summation. 
B)  spatial summation. 
C)  tetanus. 
D)  the refractory state. 
E)  an action potential with an abnormally high peak of depolarization. 
A)  temporal summation. 
B)  spatial summation. 
C)  tetanus. 
D)  the refractory state. 
E)  an action potential with an abnormally high peak of depolarization.

Exam 48: Neurons, Synapses, and Signaling

The "threshold" potential of a membrane

For the following questions, refer to the graph of an action potential. -The minimum graded depolarization needed to operate the voltage-gated sodium and potassium channels is indicated by the label

Temporal summation always involves

The "selectivity" of a particular ion channel refers to its

In a simple synapse, neurotransmitter chemicals are released by

A "resting" motor neuron is expected to

The "undershoot" phase of after-hyperpolarization is due to

ATP hydrolysis directly powers the movement of

Adjacent neurons with direct (non-neurotransmitter)action potential transfer are said to have electrical synapses, based on the presence of

Neurotransmitters affect postsynaptic cells by

A simple nervous system

A graded hyperpolarization of a membrane can be induced by

When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of

Introduction: Themes in the Study of Life

The Chemical Context of Life

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The Chromosomal Basis of Inheritance

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Descent with Modification: A Darwinian View of Life

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