I searched for the answer for this question on Wikipedia and Stackexchange a lot but couldn't find same question or a required answer in some other similar question.
I understand that the function of the salt bridge is to complete the circuit and maintain electrical neutrality in both the half cells of a galvanic cell. This is achieved by movement of cations and anion in the salt bridge. The anions move towards the anodic half cell and cations move towards the cathodic half cell.
My question is: are these cations and anions provided by the salt bridge itself and as such, do they deplete over time as the electrochemical reaction progresses?
Is the salt bridge just a medium that is passing the anions from the solution of the cathodic cell to the anodic cell and passing the cations from the solution of the anodic cell to the cathodic cell?
Do both of these mechanisms take place?
I will be grateful for insight on this topic.