Question 1

Which would result from an increase in the extracellular concentration of K+ above normal?

Accepted Answer

A)  depolarization of resting nerve cells 
B)  hyperpolarization of resting nerve cells 
C)  The potassium equilibrium potential of nerve cells would become more negative. 
D)  The sodium equilibrium potential would become less positive.

Question 2

Dorsal root ganglia contain the cell bodies of efferent neurons.

Accepted Answer

A) True 
 B)False

Question 3

An action potential in a neuronal membrane differs from a graded potential in that:

Accepted Answer

A)  an action potential requires the opening of Ca2+ channels, whereas a graded potential does not. 
B)  an action potential is propagated without decrement, whereas a graded potential decrements with distance. 
C)  an action potential has a threshold, whereas a graded potential is an all-or-none phenomenon. 
D)  movement of Na+ and K+ across cell membranes mediate action potentials, while graded potentials do not involve movement of Na+ and K+. 
E)  action potentials vary in size with the size of a stimulus, while graded potentials do not.

Question 4

Which best describes temporal summation?

Accepted Answer

A)  A synapse is stimulated a second time before the effect of a first stimulus at the synapse has terminated. 
B)  It only refers to addition of EPSPs. 
C)  Two synapses on different regions of a cell are stimulated at the same time. 
D)  It always brings a postsynaptic cell to threshold. 
E)  The size of an EPSP depends on the size of the stimulus.

Question 5

Opioid drugs, such as morphine, are agonists of a class of neurotransmitters called endorphins.

Accepted Answer

A) True 
 B)False

Question 6

Exocytosis of neurotransmitter into the synaptic cleft is triggered by an influx of ______ in response to the arrival of an action potential in the axon terminal.

Accepted Answer

A)  K+ 
B)  Na+ 
C)  Ca2+ 
D)  ATP 
E)  Cl-

Question 7

Which is TRUE about the initial segment of an axon?

Accepted Answer

A)  Its membrane potential at threshold is more positive than that of the cell body and dendrites. 
B)  Its membrane potential at threshold is more negative than that of the cell body and dendrites. 
C)  Synapses far from the initial segment are more effective in influencing whether an action potential will be generated in the axon than are synapses close to the initial segment. 
D)  It is the region where neurotransmitter vesicles are docked and ready to be released by exocytosis. 
E)  It can only conduct graded potentials because it lacks voltage-gated Na+ channels.

Question 8

How is the strength of a stimulus encoded by neurons?

Accepted Answer

A)  by the size of action potentials 
B)  by the frequency of action potentials 
C)  by the duration of action potentials 
D)  by whether the action potential peak is positive or negative

Question 9

Because all parts of a neuronal cell body have the same threshold, no one synapse on the cell is more important than any other.

Accepted Answer

A) True 
 B)False

Question 10

Which is one of the most abundant excitatory neurotransmittors in the CNS?

Accepted Answer

A)  Glutamate 
B)  Dopamine 
C)  Norepinephrine 
D)  Gamma-aminobutyric acid (GAB
A)  
E)  Endorphin

Question 11

Which is NOT true of myelin?

Accepted Answer

A)  It is a fatty membranous sheath. 
B)  It is formed by glial cells. 
C)  It influences the velocity of conduction of an electrical signal down an axon. 
D)  It covers all parts of the neuron, including the axon, cell body, and dendrites.

Question 12

During a hyperpolarizing graded potential, positively charged ions flow away from the site of the initial hyperpolarization on the outside of membrane and toward this site on the inside.

Accepted Answer

A) True 
 B)False

Question 13

The relative refractory period of an axon coincides with the period of

Accepted Answer

A)  activation and inactivation of voltage-dependent Na+ channels. 
B)  Na+ permeability that is greater than that during the depolarization phase. 
C)  increased K+ flux into the cell. 
D)  increased K+ permeability of the cell. 
E)  Increased Na+ flux through K+ channels.

Question 14

The regions of axon membrane that lie between regions of myelin are the

Accepted Answer

A)  ganglia. 
B)  nodes of Ranvier. 
C)  synaptic membranes. 
D)  glial cells. 
E)  pia mater.

Question 15

A graded potential in a membrane results in an electric current along an adjacent area of membrane and this current diminishes with distance from the site of the initial potential change.

Accepted Answer

A) True 
 B)False

Question 16

The equilibrium potential of K+ ions in nerve cells is about -90 mV. The membrane potential of typical nerve cells at rest is -70 mV. Therefore

Accepted Answer

A)  Increasing the permeability of a resting neuronal membrane to K+ will make the membrane potential more negative inside with respect to outside. 
B)  In resting neurons, there is a net diffusion of K+ into the cell. 
C)  changing the resting membrane potential of a neuron to -80 mV would increase K+ diffusion rate out of the cell. 
D)  potassium is the only permanent ion at rest. 
E)  there must be another permanent ion with an equilibrium potential more negative than -90 mV.

Question 17

Which of the following is NOT characteristic of the sympathetic division of the autonomic nervous system?

Accepted Answer

A)  Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissue(s). 
B)  Preganglionic neurons are short and synapse in ganglia located near the spinal cord. 
C)  Preganglionic neurons release acetylcholine at synapses with postganglionic neurons. 
D)  Postganglionic neurons release norepinephrine at their neuroeffector junctions. 
E)  Postganglionic neuron cell bodies are located in the collateral chain ganglia (sympathetic trunk).

Question 18

Which describes the response of the voltage-gated channels when an axon is stimulated to threshold?

Accepted Answer

A)  K+ channels open before the Na+ channels. 
B)  Na+ channels are activated and then inactivated. 
C)  K+ channels open at the same time as the Na+ channels. 
D)  K+ channels are opened when Na+ binds to the channel. 
E)  K+ influx causes Na+ channels to inactivate.

Question 19

SNARE receptor protein complexes in presynaptic neurons function as inhibitors of calcium transport to dampen or reduce the amount of neurotransmitter vesicles that participate in exocytosis.

Accepted Answer

A) True 
 B)False

Question 20

Postganglionic neuron cell bodies of the autonomic nervous system have which category of neurotransmitter receptor?

Accepted Answer

A)  Adrenergic receptors 
B)  Serotonin receptors 
C)  Muscarinic acetylcholine receptors 
D)  Nicotinic acetylcholine receptors 
E)  Dopamine receptors

Exam 6: Neuronal Signaling and the Structure of the Nervous System

Which would result from an increase in the extracellular concentration of K⁺ above normal?

Dorsal root ganglia contain the cell bodies of efferent neurons.

An action potential in a neuronal membrane differs from a graded potential in that:

Which best describes temporal summation?

Opioid drugs, such as morphine, are agonists of a class of neurotransmitters called endorphins.

Exocytosis of neurotransmitter into the synaptic cleft is triggered by an influx of ______ in response to the arrival of an action potential in the axon terminal.

Which is TRUE about the initial segment of an axon?

How is the strength of a stimulus encoded by neurons?

Because all parts of a neuronal cell body have the same threshold, no one synapse on the cell is more important than any other.

Which is one of the most abundant excitatory neurotransmittors in the CNS?

Which is NOT true of myelin?

During a hyperpolarizing graded potential, positively charged ions flow away from the site of the initial hyperpolarization on the outside of membrane and toward this site on the inside.

The relative refractory period of an axon coincides with the period of

The regions of axon membrane that lie between regions of myelin are the

A graded potential in a membrane results in an electric current along an adjacent area of membrane and this current diminishes with distance from the site of the initial potential change.

The equilibrium potential of K⁺ ions in nerve cells is about -90 mV. The membrane potential of typical nerve cells at rest is -70 mV. Therefore

Which of the following is NOT characteristic of the sympathetic division of the autonomic nervous system?

Which describes the response of the voltage-gated channels when an axon is stimulated to threshold?

SNARE receptor protein complexes in presynaptic neurons function as inhibitors of calcium transport to dampen or reduce the amount of neurotransmitter vesicles that participate in exocytosis.

Postganglionic neuron cell bodies of the autonomic nervous system have which category of neurotransmitter receptor?