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C2.2.3—Nerve impulses as action potentials

Nerve impulses are action potentials propagated along neuron membranes by local depolarization, ion channel opening and restoration of resting polarity.

Syllabus
First assessment 2025
Objective
C2.2.3
Level
SL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper2
Typical marks3–8

Common command terms

  • Explain
  • Outline

Recent exam appearances

November 2024Paper2 ["SL"] · TZ16(c)[ 7 ]C2.2.3—Nerve impulses as action potentials
May 2022Paper2 ["SL"] · TZ15(b)[ 1 ]C2.2.3—Nerve impulses as action potentials
May 2018Paper2 ["SL"] · TZ25(c)[ 7 ]C2.2.3—Nerve impulses as action potentials
November 2015Paper2 ["SL"] · TZ07(b)[ 8 ]C2.2.3—Nerve impulses as action potentials
May 2015Paper2 ["SL"] · TZ13(d)[ 3 ]C2.2.3—Nerve impulses as action potentials
Practice this objective

Coverage 2010–2024 · Updated 15 Jul 2026

Concept essentials

  • Action potentials are regenerated along neuron membranes.
  • Sodium ion entry causes depolarization of the membrane.
  • Potassium ion exit helps repolarize the membrane.
  • Local current from one region triggers depolarization in the next region.
ConceptIB Biology SL