Neuroscience: The Neuron Mechanism
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Questions and Answers

What is the Nernst potential for potassium ion (K+)?

  • 130 mV
  • -70 mV
  • -98 mV (correct)
  • 0 mV

    • Which factor is most important for determining the Nernst potential of an ion?

  • The specific channel conductance for that ion
  • The ratio of extracellular to intracellular concentration of the ion (correct)
  • The concentration of the ion inside the cell
  • The total amount of charge across the membrane

    • What happens to the potential if extracellular chloride ion (Cl-) concentration is increased to -70 mV?

  • It will cause hyperpolarization
  • It leads to depolarization (correct)
  • It has no effect on the potential
  • It stabilizes resting potential

    • If the Na+ channels open at a resting potential of -70 mV, what is the expected effect on the neuron?

    <p>The neuron will depolarize</p> Signup and view all the answers

    What is the Nernst potential for sodium ion (Na+)?

    <p>67 mV</p> Signup and view all the answers

    What primarily determines how quickly neurons can respond to changes in their environment?

    <p>The amount of ion channels present</p> Signup and view all the answers

    How do electrical potentials in neurons spread across the membrane?

    <p>According to the cable equation</p> Signup and view all the answers

    Which factor influences how far the membrane potential can spread in a neuron?

    <p>The diameter of the cell or cable</p> Signup and view all the answers

    What happens to a neuron's membrane voltage when it experiences depolarization?

    <p>It becomes more positively charged</p> Signup and view all the answers

    What is the nature of the reaction in neurons when ion channels are activated?

    <p>It is a fast electrical reaction</p> Signup and view all the answers

    What is the primary role of neurotransmitters in synaptic signaling?

    <p>They facilitate communication between neurons at synapses.</p> Signup and view all the answers

    How does endocrine signaling primarily differ from synaptic signaling?

    <p>Endocrine signaling involves the bloodstream for distribution.</p> Signup and view all the answers

    What is a characteristic feature of the neuron that allows for communication?

    <p>They can rapidly generate electrical signals.</p> Signup and view all the answers

    Why do neurons require a significant amount of energy, consuming approximately 20% of blood flow?

    <p>For maintaining electrical gradients and pumping ions.</p> Signup and view all the answers

    Which type of signaling is characterized by the release of hormones into the bloodstream?

    <p>Endocrine signaling</p> Signup and view all the answers

    What is the function of the soma in a neuron?

    <p>To synthesize proteins and contain DNA.</p> Signup and view all the answers

    In terms of signal delivery speed, which type of signaling is considered extremely fast?

    <p>Synaptic signaling</p> Signup and view all the answers

    What is commonly released at the end of a neuron's axon during synaptic signaling?

    <p>Neurotransmitters and neuromodulators</p> Signup and view all the answers

    What is the Nernst potential for potassium ions (K+)?

    <p>-98 mV</p> Signup and view all the answers

    Which ion concentrations influence the Nernst potential for potassium?

    Signup and view all the answers

    What is the most significant factor in determining the Nernst potential for K+?

    <p>The ratio of K+ out to K+ in</p> Signup and view all the answers

    What will happen if K+ channels open in a neuron?

    <p>The neuron will hyperpolarize</p> Signup and view all the answers

    What is the resting potential of a neuron typically characterized as?

    <p>-70 mV</p> Signup and view all the answers

    What effect does an increase in extracellular Cl- concentration have if ECl- is exactly -70 mV?

    <p>No effect on the resting potential</p> Signup and view all the answers

    Which ion channel opening would lead to the depolarization of a neuron?

    <p>Na+ channels</p> Signup and view all the answers

    The Nernst potential for Ca2+ is given as what value?

    <p>130 mV</p> Signup and view all the answers

    In order to maintain a polarized resting potential, what does the Na+K+ ATPase utilize?

    <p>ATP</p> Signup and view all the answers

    What is the Nernst Equation primarily used for?

    <p>Determining equilibrium potentials for different ions</p> Signup and view all the answers

    If a neuron reached a resting potential of -52 mV, what likely occurred?

    <p>An influx of Na+ ions</p> Signup and view all the answers

    What does a negative resting potential of -90 mV for Cl- indicate?

    <p>Cl- is more concentrated outside the neuron</p> Signup and view all the answers

    What will most likely cause hyperpolarization in a neuron?

    <p>Opening K+ channels</p> Signup and view all the answers

    What must occur for a neuron to be ready to respond to a stimulation?

    <p>It must be at resting potential</p> Signup and view all the answers

    What is the Nernst potential for K+ indicated in the information?

    <p>-98 mV</p> Signup and view all the answers

    What would be the immediate effect of opening Ca2+ channels during a neuronal stimulation?

    <p>It would cause depolarization</p> Signup and view all the answers

    What is the Nernst potential (EK+) for potassium ions (K+)?

    <p>-98 mV</p> Signup and view all the answers

    Which ion concentration ratio is critical for determining the Nernst potential for potassium (K+)?

    Signup and view all the answers

    What is the Nernst potential for potassium ion (K+)?

    <p>-98</p> Signup and view all the answers

    What happens when Na+ channels open at a resting potential of -70 mV?

    <p>67</p> Signup and view all the answers

    What is the role of the ratio between K+out and K+in in the Nernst equation?

    <p>1</p> Signup and view all the answers

    What is the expected consequence of increasing extracellular chloride (Cl-) concentration so that ECl- is -70 mV?

    <p>0</p> Signup and view all the answers

    What value represents the Nernst potential for sodium ion (Na+)?

    <p>-67</p> Signup and view all the answers

    What is the Nernst potential for chloride ion (Cl-) given in the information?

    <p>-70</p> Signup and view all the answers

    Which Nernst potential is correct for calcium ions (Ca2+)?

    <p>130</p> Signup and view all the answers

    If the resting potential is increased to -52 mV, what is likely indicated about the neuron's condition?

    <p>2</p> Signup and view all the answers

    Study Notes

    The Neuron: A Fast Reaction Device

    • Nernst Equation: Calculates the equilibrium potential for an ion across a membrane.
      • Depends on the ratio of ion concentrations inside and outside the cell.
    • Key Ions:
      • Potassium (K+): Resting potential around -98 mV.
      • Sodium (Na+): Depolarization potential around 67 mV.
      • Calcium (Ca2+): Depolarization potential around 130 mV.
      • Chloride (Cl-): Hyperpolarization potential around -90 mV.
    • Sodium-Potassium Pump (Na+/K+ ATPase): Uses ATP to maintain resting potential by pumping sodium ions out of the cell and potassium ions into the cell.
    • Depolarization: Membrane potential becomes more positive.
      • Occurs when Na+ or Ca2+ channels open, allowing these ions to flow into the cell.
    • Hyperpolarization: Membrane potential becomes more negative.
      • Occurs when K+ or Cl- channels open, allowing these ions to flow out of the cell.
    • Cable Equation: Describes how electrical potentials spread along the length of a neuron.
      • Influenced by the diameter of the neuron and the density of ion channels.
      • Determines the speed and distance of the potential propagation.
    • Neuron Function:
      • Utilizes an electrical signal.
      • Allows for fast communication across the nervous system via action potentials.
      • Releases neurotransmitters, hormones, and other substances at the end of the axon.
      • Requires a significant amount of ATP due to the constant ion pumping.
      • Soma (cell body) contains the nucleus, DNA, and machinery for protein synthesis.
      • Axon serves as the cable for signal propagation.
    • The Neuron's Environment:
      • External stimuli trigger neurons to respond.
      • The rapid response of neurons is due to the fast activation of ion channels by changes in membrane potential.
      • This process is much faster than molecular diffusion.

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    Class 3: The Nervous System Part 2 PDF

    Description

    Explore the functional dynamics of neurons with this quiz on the Nernst Equation, key ions, and the sodium-potassium pump. Understand how depolarization and hyperpolarization influence membrane potential, leading to fast reactions in nerve cells. Test your knowledge on fundamental neurophysiological concepts.

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