ACTION POTENTIAL

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Question # 1 The occurrence of an action potential can best be compared to a

    A) switch to turn a lamp on and off.
    B) volume control on a stereo.
    C) door to the classroom
    D) room light dimmer switch.

Question # 2 For sodium to accumulate rapidly in a neuron

    A) a stimulus above the threshold must open sodium gates in an accelerating manner.
    B) the wave of repolarization must occur to reestablish a resting potential.
    C) there must be a dramatic increase in the negative charge of the cytoplasm.
    D) a voltage surge must cause the sodium gates to close.
    E) the potassium gates must open first

Question # 3 The phrase "all or nothing," used in conjunction with discussion about an action potential, means that

    A) a resting membrane potential has been received by the cell.
    B) nothing can stop the action potential once the threshold is reached.
    C) the membrane either achieves total equilibrium or remains as far from equilibrium as possible.
    D) propagation along the neuron is saltatory.
    E) none of the above

Question # 4 What happens first following a neuron stimulation?

    A) Sodium ions enter the cell
    B) Sodium ions leave the cell
    C) Potassium ions enter the cell
    D) Potassium ions leave the cell.
    E) a and d above

Question # 5 Which of the following is the first response a neuron makes to a stimulus?

    A) Sodium ions enter the cell.
    B) Sodium ions leave the cell.
    C) Potassium ions enter the cell
    D) Potassium ions leave the cell.
    E) a and c above

Question # 6 Which of the following occurs first during an action potential?

    A) Many sodium ions flow into the neuron.
    B) Voltage-gated sodium channels open
    C) A local disturbance triggers the resting voltage to exceed the threshold level.
    D) The interior of the neuron becomes positive
    E) The interior of the neuron becomes negative

Question # 7 An action potential is brought about by

    A) a sudden membrane impermeability
    B) the movement of negatively charged proteins through the neuronal membrane.
    C) the movement of lipoproteins to the outer membrane.
    D) a local change in membrane permeability caused by a greater-than-threshold stimulus.
    E) all of the above

Question # 8 During the passage of a nerve impulse

    A) sodium ions pass through gated channels
    B) positive feedback causes more sodium ions to enter the cell.
    C) the interior of the cell becomes positive
    D) changing voltage increases the number of open gates.
    E) all of the above

Question # 9 An action potential is brought about by

    A) a sudden membrane impermeability
    B) the movement of negatively charged proteins through the neuronal membrane.
    C) the movement of lipoproteins to the outer membrane.
    D) a local change in membrane permeability caused by a greater-than-threshold stimulus.
    E) all of the above

Question # 10 Which of the following terms most accurately describes the cellular activity associated with the actual passage of a nerve impulse?

    A) electrical discharge
    B) action of sodium-potassium pump
    C) wave of depolarization
    D) repolarization
    E) active transport of ions

Question # 11 Once a threshold is reached,

    A) the number of sodium gates that open depends upon the strength of a stimulus.
    B) a graded local potential will be unable to spread to a trigger zone of the nerve membrane.
    C) the resting potential of a neuron is restored.
    D) the potassium channels in the input zone open.
    E) the opening of sodium gates and the accompanying flow of sodium ions is an example of positive feedback.

Question # 12 During the passage of a nerve impulse

    A) sodium ions pass through gated channels.
    B) positive feedback causes more sodium ions to enter the cell.
    C) the interior of the cell becomes positive.
    D) changing voltage increases the number of open gates.
    E) all of the above

Question # 13 During the recovery period between action potentials,

    A) the threshold value is increased.
    B) the threshold value is reduced.
    C) the sodium gates are shut and the potassium gates are opened.
    D) both the sodium and the potassium gates are shut.
    E) the nerve is said to be at the resting potential

Question # 14 What happens first following a neuron stimulation?

    A) Sodium ions enter the cell.
    B) Sodium ions leave the cell
    C) Potassium ions enter the cell.
    D) Potassium ions leave the cell.
    E) a and d above

Question # 15 The recovery time from the passage of a nerve impulse is called the

    A) polarized response.
    B) wave of depolarization.
    C) action potential propagation.
    D) refractory period.
    E) saltatory period.

Question # 16 Disturbances in sensory neurons will result in an action potential if the

    A) stimulus is graded
    B) stimulus remains local
    C) graded stimulus reaches a trigger zone
    D) localized stimuli do not spread too far
    E) stimuli become downgraded to localized ones.

Question # 17 Which statement is false?

    A) A nerve will not fire unless a stimulus exceeds the threshold.
    B) An action potential is an all-or-nothing event.
    C) An action potential continues indefinitely until a quenching signal is released.
    D) An action potential is self-propagating.
    E) An action potential transmission depends on activities at the membrane.