Physiology of Neurons: Action Potential
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Questions and Answers

Quel est le mécanisme responsable de la propagation d'un potentiel d'action le long de la membrane?

  • Fermeture des canaux Na+
  • Conduction saltatoire (correct)
  • Ouverture des canaux K+
  • Pompe ionique

Quels ions sont principalement impliqués dans la dépolarisation du potentiel d'action?

  • Calcium (Ca2+)
  • Potassium (K+)
  • Sodium (Na+) (correct)
  • Chlore (Cl-)

Quel processus physiologique est responsable de la repolarisation du potentiel d'action?

  • Fermeture des canaux K+ (correct)
  • Pompe à sodium/potassium
  • Ouverture des canaux Na+
  • Conduction saltatoire

Qu'est-ce qui provoque la période réfractaire absolue lors du potentiel d'action?

<p>Fermeture des canaux Na+ (A)</p> Signup and view all the answers

Quel type de cellule forme la myéline autour de l'axone pour favoriser la conduction saltatoire?

<p>Cellule de Schwann (A)</p> Signup and view all the answers

Que se passe-t-il au niveau du seuil pendant la génération du potentiel d'action?

<p>Les canaux sodiques (Na+) se ferment. (D)</p> Signup and view all the answers

Quel canal ionique est principalement responsable de l'entrée rapide de sodium (Na+) pendant la dépolarisation?

<p>Canal sodium (Na+) (D)</p> Signup and view all the answers

Quelle est la fonction principale de la pompe à sodium/potassium dans la cellule neuronale?

<p>Assurer l'équilibre ionique en pompant 3 Na+ vers l'extérieur et 2 K+ vers l'intérieur. (B)</p> Signup and view all the answers

Quel événement marque le début de la dépolarisation du potentiel d'action?

<p>Les canaux sodiques (Na+) s'ouvrent. (C)</p> Signup and view all the answers

Qu'est-ce qui se passe pendant l'hyperpolarisation du potentiel membranaire?

<p>La membrane devient 30 mV plus négative que le potentiel membranaire de repos. (D)</p> Signup and view all the answers

Quel est le principal rôle des nœuds de Ranvier dans la propagation du potentiel d'action?

<p>Permettre une propagation saltatoire plus rapide en sautant les zones myélinisées. (A)</p> Signup and view all the answers

Flashcards

Saltatory conduction

The conduction of an action potential along myelinated axons, where the signal jumps from one node of Ranvier to the next instead of traveling continuously along the entire axon.

Depolarization

The rapid increase in membrane potential during an action potential, caused by the influx of sodium ions into the neuron.

Repolarization

The return of the membrane potential to its resting state after depolarization, mainly caused by the efflux of potassium ions.

Absolute refractory period

A period after an action potential where the neuron is unable to generate another action potential, regardless of the strength of the stimulus.

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Schwann cells

Specialized glial cells that wrap around axons in the peripheral nervous system, forming a myelin sheath.

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Threshold

The point at which the membrane potential must reach to trigger an action potential. This is the threshold for depolarization, opening voltage-gated sodium channels.

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Voltage-gated sodium channel

A type of ion channel that is responsible for the rapid influx of sodium ions during depolarization, opening when the membrane reaches a certain threshold.

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Sodium-potassium pump

An active transport protein that pumps three sodium ions out of the cell and two potassium ions into the cell, maintaining the neuron's resting membrane potential.

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Depolarization

The process of bringing the membrane potential more positive, moving the membrane potential closer to zero.

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Hyperpolarization

A brief period during which the membrane potential becomes more negative than its resting value after repolarization. This is due to the continued efflux of potassium ions.

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Nodes of Ranvier

Gaps in the myelin sheath that surround axons, where the action potential is able to propagate quickly by jumping from node to node.

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