Question: You are a bioengineer interested in developing better nerve stimulators for prothetic limbs, such…

You are a bioengineer interested in developing better nerve
stimulators for prothetic limbs, such as arms, hands or legs. You
want to understand the membrane equilibrium potential, and the flow
of sodium ions across the typical nerve cell membrane at the onset
of depolarization for an action potential.

Use the Nerst Equation to compute the membrane equilibrium
potential for sodium (Na+), VeNa+= 62Xlog([ENa+]/[ I Na+])mV

Assume that:

a) Intracellular Na+ concentration, [ I Na+]=11.0mmol/L

b) Extracellular Na+ concentration, [ENa+]=130mmol/L

c)Threshold for opening of sodium channels, Vm=-54.4mV

d)The membrane resistance of one sodium channel. RNa+=170×10^9
ohms=170Gohms

e)The nerve cell membrane has a total area of 10um^2, containing
650 sodium channels

1) Compute the membrane equilibrium potential for sodium,
VeNa+:

2) Using the Hodgkin-Huxley Model: I Na+=(Vm-VeNa+)/RNa+ Compute
the current generated by the flow of sodium ions through a single
sodium channel in the nerve cell membrane onset of depolarization
of a nation potential: I Na+

3) What is the total current flow through the nerve cell
membrane at the onset of depolarization within the area of
10um^2?

4) There are 10^12 picoAmp in 1 Amp. Convert the answer to #3
above, to picoAmp (pA)

5) The current flow that was computed above has a minus sigh.
Does this mean that Na+ is flowing into the nerve cell, or out of
the nerve cell, during the initial depolarization of the action
potential that you have just calculated above in #2?

6)During this process, does the intracellular potential of the
nerve cell become more positive or negative relative to its
extracellular fluid(ground)?