And that's why only small inorganic ions can pass across. And finally, these ion channels are usually very specific to the type of ions they allow across that membrane. Now, what about gap junctions? Well, unlike voltage gated and ligand gate on channels, these gap junctions actually have relatively large pore sizes, so the diameter is about 20 angstroms. On top of that, they also allowed the movement of not only inorganic ions, so ions like calcium, sodium, potassium, chloride ions across that particular channel, but they also allow the movement of organic substances such as glucose molecules, amino acids, as well as nucleotides. So we see, unlike the voltage gated and ligangate on channels, which are usually specific and can only move these inorganic ions, gap junctions are non specific.