Neurophysiology: Action Potentials and Stimuli
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Questions and Answers

Why are action potentials not decremental in nature?

  • Because the action potential is initiated at one end of the neuron and propagates towards the other end
  • Because the action potential is initiated at the middle of the cell and propagates towards the ends
  • Because the action potential can propagate in either direction along the membrane
  • Because the action potential depends on the positive feedback cycle of a new group of Na+ channels (correct)

    • What is the main reason action potentials can only propagate in one direction along a membrane?

  • Because the action potential is initiated near the middle of the skeletal muscle cells and propagates towards the two ends
  • Because the velocity of propagation depends on the fiber diameter and whether the fiber is myelinated
  • Because the action potential is initiated at one end of the neuron and propagates towards the other end
  • Because the membrane area that has just undergone an action potential is refractory and cannot immediately undergo another (correct)

    • What is the relationship between the velocity of action potential propagation and the fiber diameter?

  • The smaller the fiber diameter, the faster the action potential propagates
  • The velocity of action potential propagation depends only on whether the fiber is myelinated, not on the fiber diameter
  • The larger the fiber diameter, the faster the action potential propagates (correct)
  • The fiber diameter has no effect on the velocity of action potential propagation

    • Under what condition can action potentials propagate in either direction along an excitable membrane?

    <p>If the membrane through which the action potential must travel is not refractory</p> Signup and view all the answers

    Where are action potentials typically initiated in most neurons?

    <p>At one end of the neuron and propagate towards the other end</p> Signup and view all the answers

    What happens to the action potential when it reaches the end of an axon?

    <p>It is unable to propagate further and the propagation ceases</p> Signup and view all the answers

    What is the term used to describe the stimuli that cause subthreshold potentials?

    <p>Subthreshold stimuli</p> Signup and view all the answers

    According to the all-or-none law, what is true about action potentials?

    <p>Action potentials either occur maximally or they do not occur at all</p> Signup and view all the answers

    What happens during the absolute refractory period of an action potential?

    <p>The voltage-gated Na+ channels are already open or in an inactivated state</p> Signup and view all the answers

    What is the effect of anesthetics on nerve cells?

    <p>Anesthetics suppress the formation and transmission of nerve impulses</p> Signup and view all the answers

    What is the relationship between the amplitude of an action potential and the stimulus intensity?

    <p>The amplitude of the action potential is constant above the threshold level</p> Signup and view all the answers

    What is the purpose of the refractory period in the generation of action potentials?

    <p>To prevent the generation of a second action potential during the action potential</p> Signup and view all the answers

    What is the primary reason that voltage-gated Na+ channels open before voltage-gated K+ channels during membrane depolarization?

    <p>Voltage-gated Na+ channels have a faster response time to changes in membrane potential compared to voltage-gated K+ channels.</p> Signup and view all the answers

    What is the primary function of the inactivation gate in voltage-gated Na+ channels?

    <p>To limit the influx of Na+ ions through the channel after it has opened.</p> Signup and view all the answers

    Which of the following is a key difference between voltage-gated Na+ and K+ channels during the action potential?

    <p>Voltage-gated Na+ channels open faster, but close slower than voltage-gated K+ channels.</p> Signup and view all the answers

    What is the purpose of the refractory period during an action potential?

    <p>To prevent the cell from generating multiple action potentials in rapid succession.</p> Signup and view all the answers

    What is the significance of the 'all-or-none' law in the context of action potentials?

    <p>It suggests that the action potential is an all-or-nothing event, with no intermediate or partial responses possible.</p> Signup and view all the answers

    What is the relationship between subthreshold potentials and the generation of an action potential?

    <p>Subthreshold potentials can summate to eventually reach the threshold potential and trigger an action potential.</p> Signup and view all the answers

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