<prompt> Hypokalemia causes:Increased amplitude of action potentialHyperpolarisationResting membrane potential becomes less negativeTetany  <response>: Decreasing the external hyponatremia reduces the size of the AP but has little effect on RMP. Decrease in extracellular hypocalcaemia increases the excitability of nerve and muscle cells by increasing the permeability of sodium channels. 50 of normal cause spontaneous discharge in some peripheral nerves known as tetany. An increase in extracellular hypercalcemia can stabilize the membrane by decreasing excitability If the extracellular level of K is increased hyperkalemia, the resting potential moves closer to the threshold depolarisation for eliciting an action potential and the neuron becomes more excitable. If the extracellular level of K is decreased hypokalemia, the membrane potential is reduced and the neuron is hyperpolarized. 