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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
HL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2022
Most common paperPaper2
Typical marks1–3

Common command terms

  • Explain
  • Outline

Recent exam appearances

May 2022Paper2 ["HL"] · TZ13(b)[ 1 ]C2.2.3—Nerve impulses as action potentials
November 2021Paper2 ["HL"] · TZ03(c)[ 3 ]C2.2.3—Nerve impulses as action potentials
May 2018Paper1 ["HL"] · TZ236[ 1 ]C2.2.3—Nerve impulses as action potentials
November 2015Paper2 ["HL"] · TZ06(b)[ 8 ]C2.2.3—Nerve impulses as action potentials
May 2014Paper1 ["HL"] · TZ121[ 1 ]C2.2.3—Nerve impulses as action potentials
Practice this objective

Coverage 2012–2022 · 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 HL