Human heart and blood flow: interactive simulation
The human heart is really two pumps side by side. The right side sends deoxygenated blood to the lungs, and the left side sends oxygenated blood to the rest of the body.
Useful for: NEET, CBSE Boards
Try this
Press Play to follow one drop of blood all the way round, or step through it yourself. Blue is deoxygenated blood and red is oxygenated.
- 1
Step to the pulmonary artery and then the pulmonary veins.
What you should see
The pulmonary artery carries deoxygenated blood and the pulmonary veins carry oxygenated blood — the exceptions to the usual rule.
- 2
Count how many times blood passes through the heart in one full round.
What you should see
Twice: once through the right side, once through the left. This is double circulation.
- 3
Find the valve between the left atrium and the left ventricle.
What you should see
The bicuspid (mitral) valve. The right side has the tricuspid valve.
- 4
Compare the left and right ventricles.
What you should see
The left ventricle has the thicker wall because it pumps blood to the whole body.
Formulas behind it
Common mistakes
- Saying all arteries carry oxygenated blood. Arteries carry blood away from the heart, whatever its oxygen level.
- Swapping the tricuspid and bicuspid valves.
- Thinking the right side of the diagram is the heart’s right side. Diagrams are drawn as if facing the person.
FAQ
Why is double circulation useful?
Oxygenated and deoxygenated blood never mix, so the body gets blood with the most oxygen at high pressure.
What makes the heart beat on its own?
The SA node in the right atrium starts each beat, so it is called the pacemaker. The heart is myogenic.
What causes the “lub-dub” sound?
Lub is the closing of the tricuspid and bicuspid valves; dub is the closing of the semilunar valves.
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