Question 1

Refer to the following graph of an action potential to answer the question.  The membrane's permeability to sodium ions is greatest at label ________.

Accepted Answer

A)   A
B)   B
C)   C
D)   D Disallow randomisation

Question 2

Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarise the middle of the axon to threshold, using an electronic probe, then ________.

Accepted Answer

A)   no action potential will be initiated
B)   an action potential will be initiated and proceed only in the normal direction toward the axon terminal
C)   an action potential will be initiated and proceed only back toward the axon hillock
D)   two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock

Question 3

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 cell

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.

Question 5

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 6

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 7

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)

Question 8

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 centre, and effectors (motor neurons)

Exam 48: Neurons, Synapses, and Signalling

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

Correct Answer
verified

Why are action potentials usually conducted in one direction?

Correct Answer
verified

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

Correct Answer
verified

Action potentials move along axons ________.

Correct Answer
verified

Refer to the following graph of an action potential to answer the question. The membrane's permeability to sodium ions is greatest at label ________.

Correct Answer
verified

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

Correct Answer
verified

The three stages of information processing in animals include ________.

Correct Answer
verified

Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarise the middle of the axon to threshold, using an electronic probe, then ________.

Correct Answer
verified

Exam 48: Neurons, Synapses, and Signalling

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

Correct AnswerverifiedShow Answer

Why are action potentials usually conducted in one direction?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Action potentials move along axons ________.

Correct AnswerverifiedShow Answer

Refer to the following graph of an action potential to answer the question. The membrane's permeability to sodium ions is greatest at label ________.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The three stages of information processing in animals include ________.

Correct AnswerverifiedShow Answer

Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarise the middle of the axon to threshold, using an electronic probe, then ________.

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