How does the circulatory system work?

Five litres of blood go round your body about once a minute, through a network that reaches almost every cell. Arteries carry blood away from the heart, veins bring it back, and about 10 billion capillaries join them in every organ.

Read how it works: How does the circulatory system work? · The history of the circulation · More boxes on Glassbox

Chapters in this interactive model

1. A network in every part of you: One pump, two kinds of pipes out and back, and a mesh of tiny tubes in between.
2. Two loops, one lap a minute: Follow one red blood cell to the lungs, back to the heart, out to an organ and home.
3. From 120 over 80 to almost nothing: Why pressure falls along the way, why tiny tubes matter most, and what the walls are like.
4. Swap at the capillaries, squeeze back home: Where blood finally does its job, and how it climbs back up your legs.
5. What blood is, and how it plugs a leak: Red cells, white cells, platelets and plasma, and the chain reaction that makes a clot.
6. When the pipes and the blood go wrong: High blood pressure, clogged arteries, heart attack and stroke, varicose veins, anaemia, and giving blood.