People who inherit familial periodic paralysis often develop very low blood potassium concentrations. How would you explain that the paralysis may disappear quickly when potassium
ions are administered intravenously?

When potassium is injected intravenously it is pumped back by the sodium-potassium pump(Na+-K+). Then, resting potential is reestablished and causes the nerves to go back to their normal state (muscles contract normally.)