<prompt> Conduction along membrane is dependent on all of the following EXCEPT: March 2013Ca2KFe2Na  <response>: Ans. C i.e. Fe2 A decrease in extracellular Ca2 concentration increases the excitability of nerve and muscle cells by decreasing the amount of depolarization necessary to initiate the changes in the Na and K conductance that produce the action potential. Conversely, an increase in extracellular Ca2 concentration can stabilize the membrane by decreasing excitability. 