#sa node

Arguably, the most famous electrical current within our bodies, is our heart rhythm. Hearts contain within them, a grouping of cells known as your Sinoatrial node (SA node). The cells within the SA node, sometimes called the pacemaker of the heart, contain electrolytes both inside and outside of the cells. The most common electrolytes within the body are sodium, potassium, calcium, magnesium, phosphorus, and chloride. Sodium and calcium generally reside outside the SA nodes cells. Potassium generally lies within them. The cell membrane acts as a barrier between these electrolytes.

Pressure within the bloodstream allows sodium to enter the cell causing potassium to leave it. Less potassium leaves the cell than sodium entering it. The result is a continually growing positive charge. When that charge reaches a certain point, calcium channels in the cell membrane open up and allow for calcium to enter. This makes the interior of the cell extremely positive compared to outside the cell, known as an action potential. Once that potential reaches a certain point, it has enough “power” to discharge down the nerves of the heart. This electricity causes the muscles to contract and your heart to beat. Ah, the wonders of chemistry in action!

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