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 cell's inside is more negative than the outside.E) A) and C)
F) B) and D)

Question 2

A chemical that affects neuronal function but is not stored in presynaptic vesicles is ________.

Accepted Answer

A)   acetylcholine
B)   epinephrine
C)   nitric oxide
D)   gamma-aminobutyric acid (GAB
A)  E) All of the above
F) A) and C)

Question 3

The heart rate of a vertebrate will decrease in response to the arrival of ________.

Accepted Answer

A)   acetylcholine
B)   endorphin
C)   nitric oxide
D)   gamma-aminobutyric acid (GAB
A)  E) B) and C)
F) A) and B)

Question 4

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 sodium channels.
C)   The axon hillock has a higher membrane potential than the terminals of the axon.
D)   Voltage-gated channels for both Na⁺ and K⁺ open in only one direction.E) B) and D)
F) A) and D)

Question 5

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish. Action potentials are found to pass more rapidly along the fish's neurons. What is the most likely explanation?

Accepted Answer

A)   The fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.
B)   Unlike the crab, the fish's axons are wrapped in myelin.
C)   There are more ion channels in the axons of the crab compared with fish axons.
D)   Unlike the crab, the fish's axons are wrapped in myelin, and the fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.E) All of the above
F) A) and D)

Question 6

Of those listed, which event occurs first following a depolarizing stimulus applied to 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) A) and B)
F) None of the above

Question 7

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

Accepted Answer

A)   because the Na⁺ concentration is much lower outside the cell than it is inside
B)   because the Na⁺ ions are actively transported by the sodium-potassium pump into the cell
C)   because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are attracted to the negatively charged interior
D)   because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are actively transported by the sodium-potassium pump into the cellE) B) and C)
F) A) and D)

Question 8

The amino acid that operates at most inhibitory synapses in the brain is ________.

Accepted Answer

A)   acetylcholine
B)   endorphin
C)   nitric oxide
D)   gamma-aminobutyric acid (GAB
A)  E) A) and B)
F) All of the above

Exam 48: Neurons, Synapses, and Signaling

The amino acid that operates at most inhibitory synapses in the brain is ________.

Correct Answer
verified

The heart rate of a vertebrate will decrease in response to the arrival of ________.

Correct Answer
verified

Why are action potentials usually conducted in one direction?

Correct Answer
verified

Of those listed, which event occurs first following a depolarizing stimulus applied to the presynaptic membrane of an axon terminal?

Correct Answer
verified

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

Correct Answer
verified

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish. Action potentials are found to pass more rapidly along the fish's neurons. What is the most likely explanation?

Correct Answer
verified

A chemical that affects neuronal function but is not stored in presynaptic vesicles is ________.

Correct Answer
verified

What happens when a resting neuron's membrane depolarizes?

Correct Answer
verified

Exam 48: Neurons, Synapses, and Signaling

The amino acid that operates at most inhibitory synapses in the brain is ________.

Correct AnswerverifiedShow Answer

The heart rate of a vertebrate will decrease in response to the arrival of ________.

Correct AnswerverifiedShow Answer

Why are action potentials usually conducted in one direction?

Correct AnswerverifiedShow Answer

Of those listed, which event occurs first following a depolarizing stimulus applied to the presynaptic membrane of an axon terminal?

Correct AnswerverifiedShow Answer

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

Correct AnswerverifiedShow Answer

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish. Action potentials are found to pass more rapidly along the fish's neurons. What is the most likely explanation?

Correct AnswerverifiedShow Answer

A chemical that affects neuronal function but is not stored in presynaptic vesicles is ________.

Correct AnswerverifiedShow Answer

What happens when a resting neuron's membrane depolarizes?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified