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 (A)</p>
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In neurons, which ions have a high concentration outside the membrane at rest?

<p>Sodium and Potassium (C)</p>
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What is the primary driving force for ions across the neuronal membrane?

<p>Both concentration and electrical gradients (B)</p>
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Which type of channels are always open and responsible for passive movement of ions in neurons?

<p>'Leak channels' (B)</p>
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Which type of ion channels in neurons are triggered by a change in membrane potential?

<p>'Voltage-gated channels' (C)</p>
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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 (A)</p>
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What is the threshold value that has to be reached to trigger an action potential?

<p>-50mV (B)</p>
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Which type of ion enters the cell, making the membrane more positive during depolarization?

<p>Na+ (A)</p>
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What happens to potassium (K+) channels during the repolarization stage?

<p>They close rapidly (A)</p>
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What causes 'overshoot' during an action potential?

<p>Slow closure of Na+ channels (B)</p>
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Which event triggers the opening of potassium (K+) channels during an action potential?

<p>Voltage event (A)</p>
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When are sodium channels completely inactivated during an action potential?

<p>From threshold until resting potential (D)</p>
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What contributes to making the membrane more negative than usual during hyperpolarization?

<p>Slow closure of K+ channels (B)</p>
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How is the resting membrane potential restored following an action potential?

<p>By K+ leak and the sodium-potassium pump (C)</p>
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What contributes to contiguous conduction during an action potential?

<p>Presence of myelin sheath (A)</p>
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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>
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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>
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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>
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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>
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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>
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Sodium voltage-gated ion channels have both activation and inactivation gates.

<p>True (A)</p>
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Potassium voltage-gated ion channels have two gates - activation and inactivation gates.

<p>False (B)</p>
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During depolarization, potassium ions enter the cell, making the membrane more positive.

<p>False (B)</p>
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The threshold value required to trigger an action potential is +50mV.

<p>False (B)</p>
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During hyperpolarization, the membrane potential becomes less negative than usual.

<p>False (B)</p>
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2 forms of refractory periods?

<p>Absolute and relative</p>
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what effects the speed of propagation?

<p>axon diameter and myelination</p>
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in relative refractory period, AP is possible with larger stimuli

<p>True (A)</p>
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