This contraction increases pressure inside the ventricles, forcing the AV valves to close to prevent blood from flowing backward into the upper chambers (atria).
She drew a quick sketch on the exam paper: four rooms, four doors. “The lub is the first sound. It happens when your heart squeezes to push blood out. Those two big doors at the top—the mitral and tricuspid valves— snap shut. Hard. Like slamming two car doors at once.” what causes the lub dub sound of the heartbeat
In a healthy heart, blood flows smoothly (laminar flow). However, if a valve does not open fully (stenosis) or does not close completely (regurgitation), the blood flow becomes turbulent. This turbulence creates a "whooshing" or "swishing" sound known as a . It happens when your heart squeezes to push blood out
Here is an informative breakdown of what causes the "lub-dub" sound, the mechanics behind it, and why it is vital for survival. Like slamming two car doors at once
“All day, every day. Two pairs of doors, slamming in perfect sequence. Lub from the incoming valves. Dub from the outgoing ones.” She paused. “Unless something’s wrong. Then it’s not lub-dub . It’s lub-shhh-dub , or lub-dub-whoosh . That’s a murmur. A leaky or stiff door.”
The period between the "lub" and the "dub." The heart is actively pumping blood into the arteries.