Change in ionic concentrations during an action potential (15 points): This question will calculate how much the concentration of intracellular sodium ions changes

during an action potential. Typically, neurons have intracellular and extracellular sodium concentrations of 15 and 150 mM, respectively. This spherical neuron of a radius of 10 m.

a) Calculate the total number of sodium ions inside the cell body using 15 mM intracellular sodium concentration. (1 mole contains 6x10^23 molecules).

answer = 3.8x10^10 ion molecules

b) Assume that all positive charges moving across the membrane during the action potential are sodium ions. Then, using the result of (a), calculate the percentage of change in sodium ion concentration in the cell body. Do you find this result surprising? Note that a unit charge is equivalent to 1.6x10-19 coulomb.

c) Explain why you cannot use Nernst or Goldman equation to calculate the change in the sodium ion concentration inside the cell during an action potential.

Need answers B and C please