The ion primarily responsible for depolarization in pacemaker cells is whereas the ion primarily responsible for this in other cardiac cells is

1. Calcium
2. Sodium

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The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass