1.   Many contain potassium salts to counteract the loss of potassium ions from the body during diarrhoea.

2.   Typically, sodium ions are excluded and potassium ions are hoarded.

3.   Cells in the heart suck potassium ions in and push sodium ions out.

4.   Inside cells, the concentration of sodium ions is usually lower and the concentration of potassium ions is higher than outside cells.

5.   The visual neurons, which had fired abnormally during the cortical spreading depression, had released large amounts of potassium ions.

6.   This lets electrically charged atoms called ions, including calcium, sodium or potassium ions, flow through.

7.   This inside-outside difference is achieved by pumps in the cell membrane that work like submicroscopic waterwheels, exchanging sodium ions for potassium ions.

8.   When the neuron is stimulated, sodium ions rush into the cell and potassium ions rush out, leaving the neuron with a positive electrochemical charge.