ANATOMY
Electrical System
Unlike the muscles in your arm or leg, you cannot voluntarily control the contraction of your heart muscle. Your heart contracts and relaxes on its own because of a specialized electrical system in your heart itself. This special tissue carries electrical signals along pathways through your heart every time it beats. This system ensures that all four chambers of your heart beat in the proper sequence.
In a healthy heart, the electrical signal begins in the sinoatrial node (also called the sinus node or SA node), and then travels throughout the heart. Located in the right atrium, the SA node is the natural pacemaker for the heart and typically initiates 60 to 80 heartbeats a minute in the average person at rest. If a person is active or exercising and the body needs more oxygen, the SA node increases the heart rate accordingly.
If the SA Node is creating a normal heartbeat, the heart is said to be in normal sinus rhythm. If the heart's electrical system is interrupted, delayed or stopped, heart rhythm disturbances (arrhythmias) may result. |
