Which ion is primarily responsible for conducting electrical impulses in the heart?

The ion primarily responsible for conducting electrical impulses in the heart is sodium. During the depolarization phase of an action potential in cardiac muscle cells, sodium ions rapidly enter the cells through specific channels, causing a change in membrane potential that initiates the electrical signal required for contraction. This influx of sodium ions leads to the rapid transmission of signals throughout the heart, ensuring that the heart beats in a coordinated manner.

While calcium and potassium also play crucial roles in the cardiac action potential and the overall function of the heart, sodium is the key player during the initial phase of depolarization that sets off the electrical activity. Calcium is more involved in the contraction process following depolarization, and potassium helps in repolarization, restoring the cell to its resting state after the impulse has passed. Magnesium, although essential in many cellular processes, does not primarily conduct electrical impulses in the heart.