The concentration of calcium ions within the neurons is approximately 100 nM, and the concentration outside of the cells is approximately 1 to 2 mM. As we already mentioned, the regulation of calcium plays a central role in the proper functioning and survival of neurons.
Normal neurons are able to regulate calcium concentration very effectively.
Voltage gated channels and ligand gated channels are important for signal transmission in neurons. Sodium and calcium get into the cell this way. But, the amount of this ions inside the cell has to be regulated to allow the neurons to carry out their functions and avoid toxic levels of the ions, which will lead to the cells' demise. On the cell membrane there are pumps which help carry out this function. Calcium is also sequestered into intracellular stores and bound by calcium binding proteins in the cytosol.