• 22 parts
  • Checked September 2026

Cardiac Cycle Quiz

One heartbeat on a chart: find each phase, curve, valve event, wave and sound.

Cardiac Cycle Quiz

Name Date

Isovolumic contraction: tap it

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Write the name of each numbered part.Answer key

  1. Atrial systole
  2. Isovolumic contraction
  3. Ventricular ejection
  4. Isovolumic relaxation
  5. Ventricular filling
  6. Aortic pressure
  7. Ventricular pressure
  8. Atrial pressure
  9. Dicrotic notch
  10. AV valves close
  11. Semilunar valves open
  12. Semilunar valves close
  13. AV valves open
  14. S1 (first heart sound)
  15. S2 (second heart sound)
  16. Ventricular volume
  17. End-diastolic volume (EDV)
  18. End-systolic volume (ESV)
  19. Stroke volume
  20. P wave
  21. QRS complex
  22. T wave

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the four valves up close

All 22 parts on the diagram

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The five phases 5

  1. Atrial systole It follows the P wave. The atria contract and push the last of their blood into the ventricles.
  2. Isovolumic contraction The ventricles contract with all four valves closed. So their volume does not change. It is also called isovolumetric contraction.
  3. Ventricular ejection Ventricular pressure is above the pressure in the aorta and pulmonary trunk. So blood is pumped out.
  4. Isovolumic relaxation The ventricles relax with all four valves closed. So their volume does not change. It is also called isovolumetric relaxation.
  5. Ventricular filling Most of the filling happens here, before the atria contract. The textbook calls it late ventricular diastole.

Pressures and valves 8

  1. Aortic pressure Pressure in the aorta. It rises while the ventricle ejects blood and falls slowly through the rest of the beat.
  2. Ventricular pressure Pressure in the left ventricle. It is low while the ventricle fills and highest during ejection.
  3. Atrial pressure Pressure in the left atrium. It rises a little when the atrium contracts and again while it fills.
  4. Dicrotic notch A small dip in the aortic pressure curve. It comes as the semilunar valves close.
  5. AV valves close The tricuspid and mitral valves close as the ventricles start to contract. Their closing makes the first heart sound.
  6. Semilunar valves open The aortic and pulmonary valves are pushed open and ejection begins.
  7. Semilunar valves close The aortic and pulmonary valves close and stop blood flowing back. Their closing makes the second heart sound.
  8. AV valves open The tricuspid and mitral valves are pushed open. The ventricles begin to fill.

Volume, ECG and sounds 9

  1. S1 (first heart sound) The sound of the atrioventricular valves closing, described as lub.
  2. S2 (second heart sound) The sound of the semilunar valves closing, described as dub.
  3. Ventricular volume The volume of blood in the ventricle. It falls during ejection and rises again as the ventricle fills.
  4. End-diastolic volume (EDV) The volume in the ventricle at the end of filling. This is just before it contracts.
  5. End-systolic volume (ESV) The volume still in the ventricle at the end of contraction.
  6. Stroke volume The blood pumped out in one beat: end-diastolic volume minus end-systolic volume.
  7. P wave It marks the depolarization of the atria, just before they contract.
  8. QRS complex It marks the depolarization of the ventricles, just before they contract.
  9. T wave It marks the repolarization of the ventricles, as they begin to relax.

How this list was compiled: Every name and detail checked on 2026-09-30 against OpenStax Anatomy and Physiology 2e, section 19.3 Cardiac Cycle (the phases, the valves, end-diastolic and end-systolic volume, stroke volume, the dicrotic notch, the ECG waves and the two heart sounds), https://openstax.org/books/anatomy-and-physiology-2e/pages/19-3-cardiac-cycle, and against Wikipedia, text only: Cardiac cycle, Wiggers diagram, Heart sounds, End-diastolic volume, End-systolic volume, Stroke volume, https://en.wikipedia.org/wiki/Wiggers_diagram. All wording is our own. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. The curves are schematic. Licence: own work

How it works

This cardiac cycle quiz uses a schematic chart of one heartbeat, the kind a physiology course calls a Wiggers diagram. Three charts share one time axis: pressures, valves and heart sounds, then ventricular volume and the ECG.

Read the full guide

Five phases on one time axis

The dashed lines divide the beat into atrial systole, isovolumic contraction, ventricular ejection, isovolumic relaxation and ventricular filling. The curves show order and direction only: no scale is printed, and the two short isovolumic phases are drawn wider than they last.

Valves follow pressure

A valve opens or closes where two pressure curves cross. The AV valves close when ventricular pressure rises above atrial pressure, and the semilunar valves open when it rises above aortic pressure. Both steps reverse as the ventricle relaxes.

  • In both isovolumic phases all four valves are closed, so the volume curve is flat.
  • S1 comes with the closing of the AV valves, S2 with the closing of the semilunar valves.

Questions and answers

What are the phases of the cardiac cycle?

Atrial systole, then ventricular systole in two parts, isovolumic contraction and ventricular ejection, then ventricular diastole in two parts, isovolumic relaxation and ventricular filling. One cycle runs from the contraction of the atria to the end of ventricular relaxation.

What is isovolumic contraction?

The first part of ventricular systole. The ventricles contract and their pressure rises, but the AV valves have closed and the semilunar valves have not yet opened, so no blood leaves and the volume stays the same.

What causes the heart sounds S1 and S2?

Valves closing. S1, the lub, is the closing of the atrioventricular valves as the ventricles begin to contract. S2, the dub, is the closing of the semilunar valves as the ventricles begin to relax.

What is stroke volume?

The amount of blood one ventricle pumps out in one beat. It is the end-diastolic volume, the blood in the ventricle when filling ends, minus the end-systolic volume, the blood still there when contraction ends.

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