The heart has a built-in electrical system that controls its rhythmic beating. This system generates electrical signals that trigger the heart muscle to contract, pumping blood throughout the body. The process starts in the upper chambers (atria), which contract to push blood into the lower chambers (ventricles). The ventricles then contract, forcefully pumping blood to the rest of the body.
This coordinated sequence of contractions is made possible by the heart's intricate electrical wiring, which ensures that each chamber contracts at the right time.
We often don't notice our heartbeat, but when we exercise, we can feel it pounding in our chest or neck. Our heart's ability to speed up and slow down is thanks to its intricate electrical system, much like the wiring in a television. This system includes specialized pacemaker cells that act as electrical outlets, sending signals to the heart muscle to contract.
Without this electrical system, our heart wouldn't be able to pump blood. This would prevent oxygen and nutrients from reaching our body's cells. If blood flow to the brain stops, consciousness is lost within seconds, and death can follow shortly after.
You may have heard of people who rely on artificial pacemakers to regulate their heartbeat. These devices mimic the natural pacemaker system, coordinating the contractions of the heart's upper and lower chambers.
In a healthy heart, a natural pacemaker called the sinoatrial (SA) node is responsible for initiating the heartbeat. Located in the right atrium, this "master pacemaker" sends out electrical signals in a regular rhythm, prompting the heart muscle to contract.
The electrical signal, originating from the sinus node, first spreads through the atria, causing them to contract. This wave-like spread is similar to a pebble dropped into a pool of water. The signal then reaches the atrioventricular (AV) node, a crucial connection point between the atria and ventricles. This node plays a vital role in ensuring that the signal reaches the ventricles, the heart's primary pumping chambers.
The electrical signal then reaches the atrioventricular (AV) node, another natural pacemaker. As the signal progresses, it travels through the bundle of His, which divides into smaller branches that extend into the left and right ventricles. These branches further divide into fine fibers that deliver the electrical signal to the ventricle muscles. This triggers the ventricles to contract, pumping blood into the arteries.
In a healthy heart, these electrical signals occur approximately once per second, maintaining the heart's steady, rhythmic beat.