The heart pumps blood throughout the entire body. But what makes the heart pump? The heart’s natural pacemaker, the Sino Atrial node or SA node, a cluster of cells is what keeps the heart rate. The heart is made up of four chambers and the SA node is at the top right chamber or the right atrium that begins the process of the heart pumping.
Actually, the SA node has the ability to spontaneously generate an electrical impulse.1 The next logical question is how can cells in the body generate electricity on it’s own. After all electricity is the presence and flow of electric charge. The separation of positive charge and negative charge across the membrane of the cell creates potential energy that can be directed.
As a matter of fact, the charges in the cell originate through, calcium (Ca++), potassium (K+), and sodium (Na+) ions and the movements of these charges across the cell membrane creates an electric potential. The influx of positive charge and Ca++ into the cell results in depolarization. This depolarization through ion channels builds up until an action threshold is triggered and the charge is released. Then the ion channels open in the opposite direction, it is repolarized and this cycle begins again.2
Truly, this depolarization is what generates the electric pulse that sets the rhythm and rate of the heart. As the SA node of cluster of cells generates a spontaneous electric impulse, this makes the muscle cells of the atrium contract. Then the larger chambers or ventricles of the heart contract and thus pump the blood throughout the body.
In fact, the heart beats 60 to 100 beats per minute. That is translated to about 4800 beats per hour. That in turn leads to 115,200 beats per day. And it leads to a whopping 42,048,000 beats per year. This means that the SA node fires its spontaneous electrical signal to trigger the heart to pump an enormous 3,363,840,000 times in a lifetime of 80 years.3 Amazingly that is more than 3 billion times in a lifetime maintaining a steady rhythm and rate in a spontaneous manner. That is the beauty of the spark of life.