• 16 parts
  • Checked September 2026

Cardiovascular System Diagram Labeled: the Path of Blood

Follow the blood round the loop, then through the four chambers and four valves.

Cardiovascular System Diagram Labeled: the Path of Blood

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
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Write the name of each numbered part.Answer key

  1. Venae cavae
  2. Right atrium
  3. Tricuspid valve
  4. Right ventricle
  5. Pulmonary valve
  6. Pulmonary trunk
  7. Pulmonary capillaries
  8. Pulmonary veins
  9. Left atrium
  10. Mitral valve
  11. Left ventricle
  12. Aortic valve
  13. Aorta
  14. Systemic capillaries
  15. Pulmonary circuit
  16. Systemic circuit

Drawn for this site on 2026-10-04 by a script. 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 same parts on a drawing of the heart

All 16 parts on the diagram

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Vessels and circuits 8

  1. Venae cavae Two large veins, the superior and inferior venae cavae. They return blood low in oxygen from the body to the right atrium.
  2. Pulmonary trunk It leads from the right ventricle toward the lungs. It divides into the left and right pulmonary arteries, the only arteries that carry blood low in oxygen.
  3. Pulmonary capillaries Gas exchange happens here: carbon dioxide leaves the blood and oxygen enters.
  4. Pulmonary veins Carry blood rich in oxygen from the lungs to the left atrium. The only veins that carry oxygen-rich blood.
  5. Aorta The great artery carrying blood rich in oxygen from the left ventricle. Every artery of the systemic circuit branches from it.
  6. Systemic capillaries Oxygen and nutrients leave the blood here for the body's cells. Carbon dioxide and wastes enter it.
  7. Pulmonary circuit The loop that takes blood from the right ventricle to the lungs. There it picks up oxygen before going back to the left atrium.
  8. Systemic circuit The loop from the left ventricle to the tissues of the body. It takes blood rich in oxygen there and brings it back to the right atrium.

Chambers and valves 8

  1. Right atrium It receives blood low in oxygen from the venae cavae. Then it passes the blood down to the right ventricle.
  2. Tricuspid valve The valve between the right atrium and the right ventricle. It closes when the ventricle contracts, so blood cannot flow back.
  3. Right ventricle The pump of the pulmonary circuit. It sends blood low in oxygen into the pulmonary trunk.
  4. Pulmonary valve The valve between the right ventricle and the pulmonary trunk. It closes when the ventricle relaxes.
  5. Left atrium It receives blood rich in oxygen from the pulmonary veins. Then it passes the blood down to the left ventricle.
  6. Mitral valve The valve between the left atrium and the left ventricle. Also called the bicuspid valve.
  7. Left ventricle The pump of the systemic circuit. It sends blood rich in oxygen into the aorta.
  8. Aortic valve The valve between the left ventricle and the aorta. It closes when the ventricle relaxes.

How this list was compiled: Every name, the order of the path and every detail line were checked on 2026-09-30 against (1) OpenStax Anatomy and Physiology 2e, 19.1 Heart Anatomy, https://openstax.org/books/anatomy-and-physiology-2e/pages/19-1-heart-anatomy, and (2) the US National Cancer Institute's SEER Training Modules, Structure of the Heart and Circulatory Pathways, https://training.seer.cancer.gov/anatomy/cardiovascular/heart/structure.html and https://training.seer.cancer.gov/anatomy/cardiovascular/blood/pathways.html. The layout, hints and detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-10-04 by a script. Own original chart; nothing traced or copied. The outlines of the lungs and the way the pulmonary arteries and veins reach both lungs are laid out after "Illu pulmonary circuit.jpg" and "Illu bronchi lungs.jpg", and the two loops after "Illu systemic circuit.jpg" (US National Cancer Institute, SEER Training Modules, undated; public domain as works of the US government, licence checked on Wikimedia Commons on 2026-10-04: https://commons.wikimedia.org/wiki/File:Illu_pulmonary_circuit.jpg, https://commons.wikimedia.org/wiki/File:Illu_bronchi_lungs.jpg, https://commons.wikimedia.org/wiki/File:Illu_systemic_circuit.jpg). Licence: own work

How it works

This path of blood through the heart diagram is a plan of the whole loop: body, right side of the heart, lungs, left side of the heart, and body again. The second view is a heart box diagram.

Read the full guide

Follow the numbers

The parts are numbered in the order blood meets them, starting as it returns from the body: venae cavae, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary trunk, pulmonary capillaries, pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta, systemic capillaries.

Two circuits, two tints

The pulmonary circuit runs from the right ventricle to the lungs and back to the left atrium. The systemic circuit runs from the left ventricle to the body and back to the right atrium. Blood low in oxygen has one tint and blood rich in oxygen another. As a circulatory system worksheet, print the chart blank; Print labeled is the label the circulatory system answer key.

  • The right side of the heart is on the left of the chart, as on a person facing you.
  • Arteries carry blood away from the heart and veins carry it back, whatever its oxygen level.

Questions and answers

What is the path of blood through the heart?

Venae cavae, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary trunk, lungs, pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta, body, and back to the venae cavae.

What are the two circuits of the cardiovascular system?

The pulmonary circuit carries blood from the right ventricle to the lungs and back to the left atrium. The systemic circuit carries it from the left ventricle to the tissues of the body and back to the right atrium.

Which blood vessels carry blood low in oxygen?

The venae cavae and the other systemic veins, and the pulmonary trunk with its arteries. The pulmonary arteries are the only arteries that carry blood low in oxygen.

Which side of the heart pumps blood to the lungs?

The right side. The right ventricle is the pump of the pulmonary circuit, and the left ventricle is the pump of the systemic circuit.

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