Nervous sytem
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Questions and Answers

What type of cells help with regulating synapses but do not send signals themselves?

  • Ependymal cells
  • Oligodendrocytes
  • Astrocytes (correct)
  • Microglia
  • Which cells are responsible for the production and movement of cerebrospinal fluid (CSF)?

  • Microglia
  • Oligodendrocytes
  • Ependymal cells (correct)
  • Astrocytes
  • What is the main function of Oligodendrocytes in the nervous system?

  • Myelination of axons (correct)
  • Regulating synapses
  • Producing CSF
  • 'Brain macrophages'
  • Which type of cells act as 'brain macrophages' to protect the brain from pathogens?

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

    In neurons, which ions have a high concentration outside the membrane at rest?

    <p>Sodium and Potassium</p> Signup and view all the answers

    What is the primary driving force for ions across the neuronal membrane?

    <p>Both concentration and electrical gradients</p> Signup and view all the answers

    Which type of channels are always open and responsible for passive movement of ions in neurons?

    <p>'Leak channels'</p> Signup and view all the answers

    Which type of ion channels in neurons are triggered by a change in membrane potential?

    <p>'Voltage-gated channels'</p> Signup and view all the answers

    How many states do sodium voltage-gated ion channels have compared to potassium voltage-gated ion channels?

    <p>Sodium has 3 states, potassium has 2 states</p> Signup and view all the answers

    What is the threshold value that has to be reached to trigger an action potential?

    <p>-50mV</p> Signup and view all the answers

    Which type of ion enters the cell, making the membrane more positive during depolarization?

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

    What happens to potassium (K+) channels during the repolarization stage?

    <p>They close rapidly</p> Signup and view all the answers

    What causes 'overshoot' during an action potential?

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

    Which event triggers the opening of potassium (K+) channels during an action potential?

    <p>Voltage event</p> Signup and view all the answers

    When are sodium channels completely inactivated during an action potential?

    <p>From threshold until resting potential</p> Signup and view all the answers

    What contributes to making the membrane more negative than usual during hyperpolarization?

    <p>Slow closure of K+ channels</p> Signup and view all the answers

    How is the resting membrane potential restored following an action potential?

    <p>By K+ leak and the sodium-potassium pump</p> Signup and view all the answers

    What contributes to contiguous conduction during an action potential?

    <p>Presence of myelin sheath</p> Signup and view all the answers

    Describe the difference in the number of gates between sodium voltage-gated ion channels and potassium voltage-gated ion channels.

    <p>Sodium channels have 2 gates (activation and inactivation gates), while potassium channels have 1 gate (activation gate).</p> Signup and view all the answers

    What is the significance of reaching the threshold value of -50mV in triggering an action potential?

    <p>The threshold value of -50mV must be reached to initiate an action potential.</p> Signup and view all the answers

    Explain the role of potassium channels during the repolarization stage of an action potential.

    <p>Potassium channels open during repolarization to allow K+ to leave the cell, restoring the net negative membrane potential.</p> Signup and view all the answers

    What causes the 'overshoot' phenomenon during an action potential?

    <p>The delayed closing of K+ channels causes the membrane potential to go more negative than usual, leading to hyperpolarization.</p> Signup and view all the answers

    Describe the process of resetting sodium channels after an action potential.

    <p>After an action potential, sodium channels quickly close and inactivate, resetting to prepare for the next action potential.</p> Signup and view all the answers

    Sodium voltage-gated ion channels have both activation and inactivation gates.

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

    Potassium voltage-gated ion channels have two gates - activation and inactivation gates.

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

    During depolarization, potassium ions enter the cell, making the membrane more positive.

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

    The threshold value required to trigger an action potential is +50mV.

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

    During hyperpolarization, the membrane potential becomes less negative than usual.

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

    2 forms of refractory periods?

    <p>Absolute and relative</p> Signup and view all the answers

    what effects the speed of propagation?

    <p>axon diameter and myelination</p> Signup and view all the answers

    in relative refractory period, AP is possible with larger stimuli

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

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