The Lub Dub Sound Of The Heartbeat | What Causes

“Perfect,” she said. “Your doors are doing their job.”

Leo mimed a slam. “ Lub. ”

“Exactly. That’s your blood saying, ‘No going back!’” She tapped the paper. “Then the heart keeps pushing. Blood shoots into the big pipes—the aorta and pulmonary artery. The second sound, the dub , happens when the heart relaxes. Those two exit doors—the aortic and pulmonic valves—slam shut. Dub. ” what causes the lub dub sound of the heartbeat

Lub-dub. Lub-dub. Lub-dub.

“So it’s not the muscle,” Leo whispered. “It’s the valves. The doors.” “Perfect,” she said

The boy, Leo, looked up. “Why does it make that sound? Like a tiny shoe inside?”

Leo pressed his own palm to his ribs. “Mine sound okay?” ” “Exactly

Elara put the stethoscope back. She listened for a long, quiet moment. The chambers filled, the valves held, the blood rushed—an ancient, invisible engine of slamming doors and fleeting silence.