What Happens During a Heartbeat

The Pulse of Life: Every heartbeat is a perfectly timed cycle of contraction and relaxation that keeps blood flowing.
The Spark Start: An electrical signal from the heart’s pacemaker (the SA node) triggers the rhythm to begin.
Chamber Coordination: The atria contract first, pushing blood into the waiting ventricles below.
Power Pump: Next, the ventricles squeeze with force, sending blood rushing to the lungs and body.
Valve Control: Tiny heart valves snap open and shut, directing blood one way and creating the “lub-dub” sound you hear.
Oxygen Loop: Blood from the lungs fills the left side of the heart, while oxygen-poor blood enters the right.
Pressure Wave: Each beat sends a pressure surge through your arteries—that’s the pulse you feel in your wrist.
Split-Second Timing: A single heartbeat lasts less than a second but coordinates billions of cells in perfect order.
Rest and Reset: Between beats, the heart relaxes and refills—ready for the next powerful push.
Endless Motion: From birth to death, this cycle repeats over 2.5 billion times—fueling every moment of your life.