The heart valves
Heart valves and papillary muscles
Four one-way valves that keep blood flowing forward through your heart.
What it does
The heart has four valves. Two sit between the upper and lower chambers and two guard the exits into the aorta and the lung artery. Their thin flaps open to let blood through and snap shut to stop it flowing back. Small muscles anchor the flaps with cords, like the strings of a parachute.
Surprising fact
The "lub-dub" of a heartbeat is the sound of the valves snapping shut, first the pair between the chambers, then the pair at the exits.
Why it matters
A valve that is too tight or leaks makes extra sounds called murmurs. Valves can now be replaced, sometimes through a tube passed up from the leg without opening the chest.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.