The heart acts like a pump and ejects the blood coming to it by contracting, thanks to electrical currents. These currents are in the order of millivolts. These currents can only be recorded by amplifying them in special devices. (electrocardiogram or ECG)
Here, the front part of the heart is removed, shown in yellow. We see the transmission system. We can think of the conduction system as "highway roads" through which electrical impulses travel very quickly within the heart. The stimulus first comes from the sinoatrial node, travels through the atria (atria), and then comes to the atrioventricular node. After waiting there for a while, it descends and stimulates the ventricles.
The heartbeat begins with an electrical stimulus from the area located above the right atrium of the heart, which consists of a specialized bundle of cells called the sinoatrial (or sinus) node. This region is known as the natural pacemaker of the heart (pacemaker).
This stimulus coming from the sinus node spreads through both atria of the heart and downwards, and the atria contract and send the blood inside them to the ventricles. Then the stimulus is sent to another special area located between the atria and ventricles; It comes to the atrioventricular (AV) node. The electrical impulse is held in the atrioventricular node for a short time before being delivered to the ventricles. Thus, the atria and ventricles do not contract at the same time.
After the contraction of the atria ends, the stimulus spreads to all ventricles through an electrical network called the His-Purkinje system, and they contract and pump the blood in them to the lungs and to the body through the aorta.
The sine node starts a new cycle by issuing another warning. Normally, around 60-100 signals come out of the sinus node per minute. This creates the heart rate.
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