Question

If the concentration of Na on side a is 7mMs and side B of the membrane the sodium concentration is 175mM what direction will sodium want to move. If In the Na is at equilibrium, what is na contribution to the membrane potential? Which side of the membrane has the more positive charge on it?

Answer 1

Answer :)

Under the only influence of concentration of ion, Sodium will move from side B to A i.e. down to its concentration gradient.

If Na is at equilibrium:

Here R is gas constant = 8.314 J.K⁻¹.mol⁻¹

T is the absolute temperature in Kelvin. Here we consider the body temperature (37⁰C).

T = 37 + 273 K

T = 310 K

The z is the valence of ions, which is +1 for Na⁺.

F = Faraday’s constant= 96,485 C.mol⁻¹

[X]_out = outside of the membrane concentration of the ion

[X]_out = 175 mM

[X]_in = inside the concentration of the ion.

[X]_in = 7 mM

By putting all values in the above formula:

E = 0.061 x 1.4

E = 0.085 V or

E = 0.085 x 1000 mV

E = +85 mV

The side B would be more positive becuase due to the high concentraiton of sodium ions, the charge on side B is +85 mV.