Neuronal Communication Mechanisms
8 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What role does calcium ($Ca^{2+}$) play in neurotransmitter release?

  • It directly opens ion channels on the postsynaptic neuron.
  • It initiates the breakdown of neurotransmitters in the synaptic cleft.
  • It binds to neurotransmitters, making them active.
  • It causes the synaptic vesicles to fuse with the presynaptic neuron's membrane. (correct)

    • Which of the following best describes the 'all-or-none' law regarding action potentials?

  • The intensity of the action potential is determined by the number of open ion channels.
  • The neuron either fires a full action potential or does not fire at all. (correct)
  • The neuron gradually increases its firing rate as the stimulus intensity increases.
  • A stronger stimulus results in a larger action potential.

    • What is the primary effect of inhibitory neurotransmitters on the postsynaptic neuron?

  • They cause depolarization by allowing sodium ($Na^+$) ions to enter the neuron.
  • They cause hyperpolarization by allowing potassium ($K^+$) ions to exit the neuron. (correct)
  • They trigger the release of calcium ($Ca^{2+}$) ions from internal stores.
  • They directly initiate the production of new neurotransmitters.

    • Which of the following is NOT a mechanism for removing neurotransmitters from the synaptic cleft?

    <p>Active transport into glial cells for storage. (A)</p> Signup and view all the answers

    What is the significance of the refractory period following an action potential?

    <p>It prevents the neuron from firing another action potential immediately. (C)</p> Signup and view all the answers

    How does spatial summation contribute to a neuron reaching its threshold for firing an action potential?

    <p>By combining signals arriving from different locations on the neuron at the same time. (B)</p> Signup and view all the answers

    If a neuron is at rest (-70mV), what membrane potential must it reach in order to fire an action potential?

    <p>-55mV (C)</p> Signup and view all the answers

    What is the difference between temporal and spatial summation?

    <p>Temporal summation means signals come from the same location, one after another, very quickly and spatial summation means signals come from different locations at the same time. (B)</p> Signup and view all the answers

    Flashcards

    Neurotransmitter Release

    The process where presynaptic neurons release neurotransmitters into the synaptic cleft.

    Action Potential

    A rapid rise and fall in electrical charge that travels down a neuron.

    Excitatory Neurotransmitters

    Chemicals that increase the likelihood of a neuron firing by causing depolarization.

    Inhibitory Neurotransmitters

    Chemicals that decrease the likelihood of a neuron firing by causing hyperpolarization.

    Signup and view all the flashcards

    Summation

    The process by which a neuron combines excitatory and inhibitory signals to determine if it will fire.

    Signup and view all the flashcards

    Refractory Period

    The phase after an action potential when a neuron cannot fire again right away.

    Signup and view all the flashcards

    Spatial Summation

    A type of summation where signals arrive from different locations simultaneously.

    Signup and view all the flashcards

    Temporal Summation

    A type of summation where signals arrive in quick succession from the same source.

    Signup and view all the flashcards

    Study Notes

    Neuronal Communication: Steps & Mechanisms

    • Neurotransmitter Release (Step 1):

      • Presynaptic neurons store neurotransmitters in vesicles within axon terminals.
      • Action potential triggers calcium (Ca²⁺) influx into the terminal.
      • Calcium prompts vesicle fusion with the membrane, releasing neurotransmitters into the synaptic cleft.
      • Neurotransmitters diffuse across the synapse.

    • Neurotransmitter Binding & Ion Channel Opening (Step 2):

      • Neurotransmitters bind to specific receptors on postsynaptic neuron dendrites.
      • Binding opens ion channels, altering the neuron's electrical potential.
      • Resting potential is -70 mV; threshold for firing is -55 mV.
      • Excitatory neurotransmitters (e.g., increasing sodium (Na⁺) influx) lead to depolarization, increasing firing likelihood.
      • Inhibitory neurotransmitters (e.g., increasing potassium (K⁺) efflux) lead to hyperpolarization, decreasing firing likelihood.
      • Neurotransmitters detach and are removed by diffusion, enzymatic breakdown, or reuptake.

    • Signal Summation (Step 3):

      • Neuron integrates excitatory (EPSPs) and inhibitory (IPSPs) signals in the soma.
      • Spatial summation: signals from different locations at the same time.
      • Temporal summation: signals from the same location in quick succession.
      • If summed signals reach -55 mV, the neuron fires an action potential.

    • Action Potential & Refractory Period (Step 4):

      • Action Potential initiation: Sodium (Na⁺) influx drives voltage to +40 mV.
      • Action potential propagates along the axon.
      • All-or-none principle: Neuron fires completely or not at all; strength of stimulus affects firing frequency, not action potential strength.
      • Repolarization : Potassium (K⁺) efflux restores the previous negative charge after firing (refractory period).
      • Neuron returns to resting potential (-70mV) preparing for another action potential.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Explore the detailed processes of neuronal communication, focusing on neurotransmitter release and their binding actions. Understand how these steps influence the electrical potential of neurons and the overall signaling within the nervous system.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser