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The Heart's Electrical System and Structure

the heartStructure/Normal Wiring
 
The heart is made up of four compartments, or "chambers," that work together to contract and pump blood.
 
The upper chambers of the heart are called atria, and their function is to receive and collect blood. The ventricles, the lower chambers, pump blood throughout the body, delivering oxygen and nutrients.
 
This coordinated action occurs when the heart is properly "wired" to send electrical signals that tell the chambers of the heart when to contract.
 
The Heart's Electrical System
 
The electrical system that runs throughout the heart's muscle tissue sends signals to the heart, telling the muscles when to contract. Without the electrical system, the heart would not pump blood and the body would not receive the oxygen and nutrients it needs.
 
Often called the heart's built-in "pacemaker," the sinus node contains the most active electrical cells and its main function is to initiate heartbeats. Other nodes transmit signals to different sections of the heart.
 
If there is a problem in any node or at any point along the electrical path, it can disrupt the regular beating of the heart and cause an arrhythmia, which is an abnormal beating of the heart. The heartbeat can become too fast or too slow, with symptoms varying based on the rhythm change. Some arrhythmias are dangerous and can cause sudden cardiac death, while others are not life-threatening.