Sinoatrial Node In The Heart Stock Photo

The SA sinoatrial node generates an electrical signal that causes the upper heart chambers atria to contract. The signal then passes through the AV atrioventricular node to the lower heart chambers ventricles, causing them to contract, or pump. The SA node is considered the pacemaker of the heart.The heart's natural pacemaker – the SA node – sends out regular electrical impulses from the top chamber (the atrium) causing it to contract and pump blood into the bottom chamber (the ventricle). The electrical impulse is then conducted to the ventricles through a form of 'junction box' called the AV node.