Question 1

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 Cl⁻
C)   increasing its membrane's permeability to Ca⁺⁺
D)   increasing its membrane's permeability to K⁺

Question 2

The fastest possible conduction velocity of action potentials is observed in ________.

Accepted Answer

A)   thin, unmyelinated neurons
B)   thin, myelinated neurons
C)   thick, unmyelinated neurons
D)   thick, myelinated neurons

Question 3

Conduction and refractory periods (states)  are typical of ________.

Accepted Answer

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

Question 4

The operation of the sodium-potassium pump moves ________.

Accepted Answer

A)   sodium and potassium ions into the cell
B)   sodium and potassium ions out of the cell
C)   sodium ions into the cell and potassium ions out of the cell
D)   sodium ions out of the cell and potassium ions into the cell

Question 5

The motor (somatic nervous)  system can alter the activities of its targets, the skeletal muscle fibers, because ________.

Accepted Answer

A)   it is electrically coupled by gap junctions to the muscles
B)   its signals bind to receptor proteins on the muscles
C)   its signals reach the muscles via the blood
D)   it is connected to the internal neural network of the muscles

Question 6

Tetrodotoxin blocks voltage-gated sodium channels, and ouabain blocks sodium-potassium pumps. If you added both tetrodotoxin and ouabain to a solution containing neural tissue, what responses would you expect?

Accepted Answer

A)   immediate loss of resting potential
B)   immediate loss of action potential with gradual shift of resting potential
C)   slow decrease of resting potential and action potential amplitudes
D)   No effect; the substances counteract each other.

Question 7

Two fundamental concepts about the ion channels of a "resting" neuron are that the channels ________.

Accepted Answer

A)   are always open, but the concentration gradients of ions frequently change
B)   are always closed, but ions move closer to the channels during excitation
C)   are open or closed depending on their type, and are specific as to which ion can traverse them
D)   open in response to stimuli, and then close simultaneously, in unison

Question 8

Which of the following will increase the speed of an action potential moving down an axon?
I.Action potentials move faster in wider axons.
II.Action potentials move faster in axons lacking potassium ion channels.
III.Action potentials move faster in myelinated axons.

Accepted Answer

A)   only I and II
B)   only II and III
C)   only I and III
D)   I, II, and III

Question 9

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)   hyperpolarize the membrane

Question 10

Most of the neurons in the human central nervous system are ________.

Accepted Answer

A)   sensory neurons
B)   motor neurons
C)   interneurons
D)   peripheral neurons

Question 11

Refer to the following graph of an action potential to answer the question.

At label ________, the cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are inactivated or becoming inactivated, and many potassium channels have opened.

Accepted Answer

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

Question 12

Neurotransmitters can affect postsynaptic cells by ________.
I.initiating signal transduction pathways in the cells
II.causing molecular changes in the cells
III.altering ion channel proteins
IV.altering the permeability of the cells

Accepted Answer

A)   I and III
B)   II and IV
C)   III and IV
D)   I, II, III, and IV

Question 13

The point of connection between two communicating neurons is called the ________.

Accepted Answer

A)   axon hillock
B)   dendrite
C)   synapse
D)   cell body

Question 14

The three stages of information processing in animals include ________.

Accepted Answer

A)   chemical senses, mechanoreception, and vision
B)   dendrites, a cell body, and an axon
C)   a presynaptic cell, neurotransmitters, and a postsynaptic cell
D)   sensory reception, an integrating center, and effectors (motor neurons)

Question 15

After the depolarization phase of an action potential, the resting potential is restored by ________.

Accepted Answer

A)   the opening of voltage-gated potassium channels and the inactivation of sodium channels
B)   a decrease in the membrane's permeability to potassium and chloride ions
C)   a brief inhibition of the sodium-potassium pump
D)   the opening of more voltage-gated sodium channels

Question 16

In a simple synapse, neurotransmitter chemicals are released by ________.

Accepted Answer

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

Question 17

When two excitatory postsynaptic potentials (EPSPs)  occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.

Accepted Answer

A)   temporal summation
B)   spatial summation
C)   tetanus
D)   the refractory state

Question 18

Action potentials move along axons ________.

Accepted Answer

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

Question 19

In a simple synapse, neurotransmitter chemicals are received by ________.

Accepted Answer

A)   the presynaptic membrane
B)   dendrites
C)   axon hillocks
D)   cell bodies

Question 20

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y. A likely explanation is that

Accepted Answer

A)   the threshold value in the postsynaptic membrane is different for cell X and cell Y.
B)   the axon of cell X is myelinated, but that of cell Y is not.
C)   only cell Y produces an enzyme that terminates the activity of the neurotransmitter.
D)   cells X and Y express different receptor molecules for this particular neurotransmitter.

Exam 48: Neurons, Synapses, and Signaling

The three stages of information processing in animals include ________.

Correct AnswerverifiedShow Answer

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y. A likely explanation is that

Correct AnswerverifiedShow Answer

Most of the neurons in the human central nervous system are ________.

Correct AnswerverifiedShow Answer

In a simple synapse, neurotransmitter chemicals are released by ________.

Correct AnswerverifiedShow Answer

A graded hyperpolarization of a membrane can be induced by ________.

Correct AnswerverifiedShow Answer

Which of the following will increase the speed of an action potential moving down an axon? I.Action potentials move faster in wider axons. II.Action potentials move faster in axons lacking potassium ion channels. III.Action potentials move faster in myelinated axons.

Correct AnswerverifiedShow Answer

Neurotransmitters can affect postsynaptic cells by ________. I.initiating signal transduction pathways in the cells II.causing molecular changes in the cells III.altering ion channel proteins IV.altering the permeability of the cells

Correct AnswerverifiedShow Answer

Refer to the following graph of an action potential to answer the question. At label ________, the cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are inactivated or becoming inactivated, and many potassium channels have opened.

Correct AnswerverifiedShow Answer

Action potentials move along axons ________.

Correct AnswerverifiedShow Answer

Conduction and refractory periods (states) are typical of ________.

Correct AnswerverifiedShow Answer

When two excitatory postsynaptic potentials (EPSPs) occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.

Correct AnswerverifiedShow Answer

Tetrodotoxin blocks voltage-gated sodium channels, and ouabain blocks sodium-potassium pumps. If you added both tetrodotoxin and ouabain to a solution containing neural tissue, what responses would you expect?

Correct AnswerverifiedShow Answer

The point of connection between two communicating neurons is called the ________.

Correct AnswerverifiedShow Answer

The motor (somatic nervous) system can alter the activities of its targets, the skeletal muscle fibers, because ________.

Correct AnswerverifiedShow Answer

Neurotransmitters categorized as inhibitory are expected to ________.

Correct AnswerverifiedShow Answer

After the depolarization phase of an action potential, the resting potential is restored by ________.

Correct AnswerverifiedShow Answer

The fastest possible conduction velocity of action potentials is observed in ________.

Correct AnswerverifiedShow Answer

The operation of the sodium-potassium pump moves ________.

Correct AnswerverifiedShow Answer

Two fundamental concepts about the ion channels of a "resting" neuron are that the channels ________.

Correct AnswerverifiedShow Answer

In a simple synapse, neurotransmitter chemicals are received by ________.

Correct AnswerverifiedShow Answer

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