While it sounds like simple onomatopoeia (a word that sounds like its meaning), "lub dub" is actually the audible sign of your heart valves snapping shut. Here is the simple breakdown of what is happening inside your chest. "Lub dub" is the sound of your heart valves closing. The "lub" happens when the valves between the upper and lower chambers close. The "dub" happens when the valves leading out of the heart to the lungs and body close. The Deep Dive: Act 1 (The Lub) The first sound, the "Lub" (medically known as S1 ), occurs at the beginning of a heartbeat.
Once that blood is pushed out, two different valves—the —snap shut to stop the blood from flowing back into the heart. what does lub dub mean
At this moment, the heart's ventricles (the strong, lower pumping chambers) contract. They squeeze to push blood upward. To prevent that blood from leaking backward into the upper chambers (the atria), two flaps called the slam shut. While it sounds like simple onomatopoeia (a word