Question 1

What happens when a resting neuron's membrane depolarizes?

Accepted Answer

A)  There is a net diffusion of Na⁺ out of the cell. 
B)  The equilibrium potential for K⁺ (EK) becomes more positive. 
C)  The neuron's membrane voltage becomes more positive. 
D)  The neuron is less likely to generate an action potential. 
E)  The cell's inside is more negative than the outside. 
A)  There is a net diffusion of Na⁺ out of the cell. 
B)  The equilibrium potential for K⁺ (EK) becomes more positive. 
C)  The neuron's membrane voltage becomes more positive. 
D)  The neuron is less likely to generate an action potential. 
E)  The cell's inside is more negative than the outside.

Question 2

Assume that a single IPSP has a negative magnitude of -0.5 mV at the axon hillock, and that a single EPSP has a positive magnitude of +0.5 mV. For a neuron with an initial membrane potential of -70 mV, the net effect of the simultaneous arrival of six IPSPs and two EPSPs would be to move the membrane potential to

Accepted Answer

A)  -72 mV. 
B)  -71 mV. 
C)  -70 mV. 
D)  -69 mV. 
E)  -68 mV. 
A)  -72 mV. 
B)  -71 mV. 
C)  -70 mV. 
D)  -69 mV. 
E)  -68 mV.

Question 3

The following steps refer to various stages in transmission at a chemical synapse.
1)Neurotransmitter binds with receptors associated with the postsynaptic membrane.
2)Calcium ions rush into neuron's cytoplasm.
3)An action potential depolarizes the membrane of the axon terminal.
4)The ligand-gated ion channels open.
5)The synaptic vesicles release neurotransmitter into the synaptic cleft.
Which sequence of events is correct?

Accepted Answer

A)  1 → 2 → 3 → 4 → 5 
B)  2 → 3 → 5 → 4 → 1 
C)  3 → 2 → 5 → 1 → 4 
D)  4 → 3 → 1 → 2 → 5 
E)  5 → 1 → 2 → 4 → 3 
A)  1 → 2 → 3 → 4 → 5 
B)  2 → 3 → 5 → 4 → 1 
C)  3 → 2 → 5 → 1 → 4 
D)  4 → 3 → 1 → 2 → 5 
E)  5 → 1 → 2 → 4 → 3

Question 4

An inhibitory postsynaptic potential (IPSP)occurs in a membrane made more permeable to

Accepted Answer

A)  potassium ions. 
B)  sodium ions. 
C)  calcium ions. 
D)  ATP. 
E)  all neurotransmitter molecules. 
A)  potassium ions. 
B)  sodium ions. 
C)  calcium ions. 
D)  ATP. 
E)  all neurotransmitter molecules.

Question 5

The release of acetylcholine from the terminal of a motor neuron is most directly linked to

Accepted Answer

A)  the entry of potassium into the axon terminal. 
B)  the exit of potassium from the axon terminal. 
C)  the entry of sodium into the axon terminal. 
D)  the exit of sodium from the axon terminal. 
E)  the entry of calcium into the axon terminal. 
A)  the entry of potassium into the axon terminal. 
B)  the exit of potassium from the axon terminal. 
C)  the entry of sodium into the axon terminal. 
D)  the exit of sodium from the axon terminal. 
E)  the entry of calcium into the axon terminal.

Question 6

The nucleus and most of the organelles in a neuron are located in the

Accepted Answer

A)  dendritic region. 
B)  axon hillock. 
C)  axon. 
D)  cell body. 
E)  axon terminals. 
A)  dendritic region. 
B)  axon hillock. 
C)  axon. 
D)  cell body. 
E)  axon terminals.

Question 7

Functionally, which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated?

Accepted Answer

A)  axonal membranes 
B)  axon hillocks 
C)  dendritic membranes 
D)  mitochondrial membranes 
E)  presynaptic membranes 
A)  axonal membranes 
B)  axon hillocks 
C)  dendritic membranes 
D)  mitochondrial membranes 
E)  presynaptic membranes

Question 8

Opening all of the sodium channels, with all other ion channels closed-which is an admittedly artificial setting-on an otherwise typical neuron should move its membrane potential to

Accepted Answer

A)  -90 mV. 
B)  -70 mV. 
C)  0 mV. 
D)  +30 mV. 
E)  +62 mV. 
A)  -90 mV. 
B)  -70 mV. 
C)  0 mV. 
D)  +30 mV. 
E)  +62 mV.

Question 9

For the following questions, refer to the graph of an action potential.
  
-The cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened at label

Accepted Answer

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

Question 10

One possible disadvantage to a nerve net is that it might conduct impulses in two directions from the point of the stimulus. Most of the synapses in vertebrates conduct information in only one direction

Accepted Answer

A)  as a result of the nodes of Ranvier. 
B)  as a result of voltage-gated sodium channels found only in the vertebrate system. 
C)  because vertebrate nerve cells have dendrites. 
D)  because only the postsynaptic cells can bind and respond to neurotransmitters. 
E)  because the sodium-potassium pump moves ions in one direction. 
A)  as a result of the nodes of Ranvier. 
B)  as a result of voltage-gated sodium channels found only in the vertebrate system. 
C)  because vertebrate nerve cells have dendrites. 
D)  because only the postsynaptic cells can bind and respond to neurotransmitters. 
E)  because the sodium-potassium pump moves ions in one direction.

Question 11

Neurotransmitters categorized as inhibitory are expected to

Accepted Answer

A)  act independently of their receptor proteins. 
B)  close potassium channels. 
C)  open sodium channels. 
D)  close chloride channels. 
E)  hyperpolarize the membrane. 
A)  act independently of their receptor proteins. 
B)  close potassium channels. 
C)  open sodium channels. 
D)  close chloride channels. 
E)  hyperpolarize the membrane.

Question 12

Self-propagation and refractory periods are typical of

Accepted Answer

A)  action potentials. 
B)  graded hyperpolarizations. 
C)  excitatory postsynaptic potentials. 
D)  threshold potentials. 
E)  resting potentials. 
A)  action potentials. 
B)  graded hyperpolarizations. 
C)  excitatory postsynaptic potentials. 
D)  threshold potentials. 
E)  resting potentials.

Question 13

Where are neurotransmitter receptors located?

Accepted Answer

A)  the nuclear membrane 
B)  the nodes of Ranvier 
C)  the postsynaptic membrane 
D)  synaptic vesicle membranes 
E)  the myelin sheath 
A)  the nuclear membrane 
B)  the nodes of Ranvier 
C)  the postsynaptic membrane 
D)  synaptic vesicle membranes 
E)  the myelin sheath

Question 14

The membrane potential that exactly offsets an ion's concentration gradient is called the

Accepted Answer

A)  graded potential. 
B)  threshold potential. 
C)  equilibrium potential. 
D)  action potential. 
E)  inhibitory postsynaptic potential. 
A)  graded potential. 
B)  threshold potential. 
C)  equilibrium potential. 
D)  action potential. 
E)  inhibitory postsynaptic potential.

Question 15

For the following questions, refer to the graph of an action potential.
  
-The membrane potential is closest to the equilibrium potential for potassium at label

Accepted Answer

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

Question 16

Why are action potentials usually conducted in one direction?

Accepted Answer

A)  The nodes of Ranvier conduct potentials in one direction. 
B)  The brief refractory period prevents reopening of voltage-gated Na⁺ channels. 
C)  The axon hillock has a higher membrane potential than the terminals of the axon. 
D)  Ions can flow along the axon in only one direction. 
E)  Voltage-gated channels for both Na⁺ and K⁺ open in only one direction. 
A)  The nodes of Ranvier conduct potentials in one direction. 
B)  The brief refractory period prevents reopening of voltage-gated Na⁺ channels. 
C)  The axon hillock has a higher membrane potential than the terminals of the axon. 
D)  Ions can flow along the axon in only one direction. 
E)  Voltage-gated channels for both Na⁺ and K⁺ open in only one direction.

Question 17

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

Accepted Answer

A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
E)  An EPSP or IPSP is generated in the postsynaptic cell. 
A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
E)  An EPSP or IPSP is generated in the postsynaptic cell.

Question 18

Action potentials move along axons

Accepted Answer

A)  more slowly in axons of large than in small diameter. 
B)  by the direct action of acetylcholine on the axonal membrane. 
C)  by activating the sodium-potassium "pump" at each point along the axonal membrane. 
D)  more rapidly in myelinated than in non-myelinated axons. 
E)  by reversing the concentration gradients for sodium and potassium ions. 
A)  more slowly in axons of large than in small diameter. 
B)  by the direct action of acetylcholine on the axonal membrane. 
C)  by activating the sodium-potassium "pump" at each point along the axonal membrane. 
D)  more rapidly in myelinated than in non-myelinated axons. 
E)  by reversing the concentration gradients for sodium and potassium ions.

Question 19

Receptors for neurotransmitters are of primary functional importance in assuring one-way synaptic transmission because they are mostly found on the

Accepted Answer

A)  axonal membrane. 
B)  axon hillock. 
C)  dendritic membrane. 
D)  mitochondrial membrane. 
E)  presynaptic membrane. 
A)  axonal membrane. 
B)  axon hillock. 
C)  dendritic membrane. 
D)  mitochondrial membrane. 
E)  presynaptic membrane.

Question 20

Neurotransmitters are released from axon terminals via

Accepted Answer

A)  osmosis. 
B)  active transport. 
C)  diffusion. 
D)  transcytosis. 
E)  exocytosis. 
A)  osmosis. 
B)  active transport. 
C)  diffusion. 
D)  transcytosis. 
E)  exocytosis.

Exam 48: Neurons, Synapses, and Signaling

What happens when a resting neuron's membrane depolarizes?

An inhibitory postsynaptic potential (IPSP)occurs in a membrane made more permeable to

The release of acetylcholine from the terminal of a motor neuron is most directly linked to

The nucleus and most of the organelles in a neuron are located in the

Functionally, which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated?

Opening all of the sodium channels, with all other ion channels closed-which is an admittedly artificial setting-on an otherwise typical neuron should move its membrane potential to

For the following questions, refer to the graph of an action potential. -The cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened at label

One possible disadvantage to a nerve net is that it might conduct impulses in two directions from the point of the stimulus. Most of the synapses in vertebrates conduct information in only one direction

Neurotransmitters categorized as inhibitory are expected to

Self-propagation and refractory periods are typical of

Where are neurotransmitter receptors located?

The membrane potential that exactly offsets an ion's concentration gradient is called the

For the following questions, refer to the graph of an action potential. -The membrane potential is closest to the equilibrium potential for potassium at label

Why are action potentials usually conducted in one direction?

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

Action potentials move along axons

Receptors for neurotransmitters are of primary functional importance in assuring one-way synaptic transmission because they are mostly found on the

Neurotransmitters are released from axon terminals via

Introduction: Themes in the Study of Life

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