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.
Leo pressed his own palm to his ribs. “Mine sound okay?” what causes the lub dub sound of the heartbeat
“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. ” Elara put the stethoscope back