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B3.2.16 (HL)—Cardiac cycle stages

The cardiac cycle coordinates diastole, atrial systole, ventricular systole, valve movements and electrical conduction to produce one-way blood flow continuously.

Syllabus
First assessment 2025
Objective
B3.2.16
Level
HL

Exam analysis

Chance of appearing8%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–4

Common command terms

  • Identify
  • State
  • Label
  • Outline
  • Describe
  • Explain

Scoring notes

Common mistake
Describing blood flow without linking it to chamber contraction or pressure changes.

Recent exam appearances

November 2024Paper3 ["HL"] · TZ022(a)[ 1 ]B3.2.16 (HL)—Cardiac cycle stages
May 2023Paper2 ["HL"] · TZ26(b)[ 4 ]B3.2.16 (HL)—Cardiac cycle stages
November 2021Paper1 ["HL"] · TZ024[ 1 ]B3.2.16 (HL)—Cardiac cycle stages
May 2019Paper1 ["HL"] · TZ229[ 1 ]B3.2.16 (HL)—Cardiac cycle stages
May 2018Paper1 ["HL"] · TZ232[ 1 ]B3.2.16 (HL)—Cardiac cycle stages
Practice this objective

Coverage 2013–2024 · Updated 15 Jul 2026

Concept essentials

  • The SA node initiates the heartbeat and atrial contraction.
  • The AV node delays the impulse before ventricular contraction.
  • Atrioventricular valves close when ventricular pressure exceeds atrial pressure.
  • Semilunar valves open when ventricular pressure exceeds arterial pressure.
  • Heart sounds are linked to valve closure during the cardiac cycle.
ConceptIB Biology HL