Neuroscience: Saltatory Conduction & Excitability
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Questions and Answers

What is one primary function of saltatory conduction in nerve fibers?

  • It increases the velocity of conduction by 5-50 fold. (correct)
  • It maximizes sodium leakage outside the fiber.
  • It decreases the velocity of conduction significantly.
  • It allows for continuous depolarization along the entire fiber.

    • Which of the following is not considered a type of stimulus that can elicit an action potential?

  • Mechanical stimuli
  • Electrical stimuli
  • Magnetic stimuli (correct)
  • Thermal stimuli

    • What is a threshold stimulus?

  • Stimulus below which no action potential can be generated.
  • A current just adequate to cause an impulse. (correct)
  • A continuous application of sub-threshold stimuli.
  • A stimulus that is unable to cause a local excitatory state.

    • Why are electrical stimuli preferred in generating action potentials?

    <p>Their intensity and duration can be easily controlled.</p> Signup and view all the answers

    How does a slowly applied stimulus affect nerve response?

    <p>It can lead to accommodation, reducing effectiveness.</p> Signup and view all the answers

    Study Notes

    Saltatory Conduction

    • Increases the speed of nerve impulse conduction by 5-50 times.
    • Nerve impulse "jumps" between nodes of Ranvier, where the myelin sheath is absent.
    • Saves energy by limiting depolarization to the nodes, minimizing sodium leakage and reducing the work needed by the sodium pump.

    Excitability

    • The ability of a cell, particularly nerve and muscle cells, to respond to a stimulus by generating an action potential.
    • Stimuli trigger depolarization of the cell membrane.
    • Types of Stimuli:
      • Mechanical (pressure, stretch, prick, crush)
      • Thermal (heat or cold)
      • Chemical (CO2, H+, acetylcholine, norepinephrine)
      • Osmotic (hydration, dehydration)
      • Electromagnetic (light waves, sound waves)
      • Electrical (preferred due to controllability, similarity to nerve impulses, and minimal damage)

    Effectiveness of Stimulus

    • Intensity:
      • Threshold stimulus: The minimum intensity required to trigger an action potential.
      • Sub-threshold stimuli: Stimuli below threshold, causing only a local, non-propagated potential.
      • Local excitatory state: The state produced by sub-threshold stimuli.
    • Rate of Application (Accommodation/Adaptation):
      • Sudden onset of stimulus is more effective than a slow rise.
      • Slow rising currents may fail to fire the nerve due to accommodation, where the cell gradually adapts to the stimulus.

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    Description

    Explore the mechanisms of saltatory conduction and the properties of excitability in nerve and muscle cells. This quiz covers the various stimuli that affect these cells and how they generate action potentials. Test your understanding of these essential physiological concepts.

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