I think you're obliquely talking about Mulder's Chart:
Certain elements block the uptake of other elements depending upon quantity. Others, increase the uptake.
Note that "cells' are living components of actual living entities. There's no such thing as 'potassium cells' or 'magnesium cells;' the smallest particles of elements are atoms, though what we often have are molecules...because the elements we use are often 'tied up' with other elements making chemical compounds. For instance, water, H2O is a compound (two hydrogen atoms, one oxygen atom) where it's smallest individual unit is a single molecule (of water).