A student is asked to find the Nernst potential of sodium at body temperature ( )

PHYSICS · Multi-part · Fermi University Physics · Biophysics & Medical Physics · Molecular machines, transport and bioenergetics · Molecular machines, transport and bioenergetics

Life at Thermal Energy, Ch The membrane: barrier, capacitor and pump

Problem

A student is asked to find the Nernst potential of sodium at body temperature (

310\,\mathrm{K}

), using

\mathrm{Na^+}

concentrations of

12\,\mathrm{mM}

inside and

145\,\mathrm{mM}

outside. Their working is shown below."

k_BT/e = 26.7\,\mathrm{mV}

310\,\mathrm{K}

. So

\begin{aligned} E_{\rm Na} &= \frac{k_BT}{e}\ln\!\left(\frac{c_{\rm in}}{c_{\rm out}}\right) \\ &= 26.7\,\mathrm{mV}\times\ln\!\left(\frac{12}{145}\right) \\ &= -66.6\,\mathrm{mV}. \end{aligned}

" ((a)) Identify the error in the working. ((b)) Give the correct value of

E_{\rm Na}

, to the nearest millivolt.

Browse the problem library