In an experimental preparation of a nerve axon, membrane potential $\left(\mathrm{E}_{\mathrm{m}}\right), \mathrm{K}^{+}$ equilibrium potential, and $\mathrm{K}^{+}$conductance can be measured. Which combination of values will create the largest outward current flow?

$\begin{array}{cccc}
& \mathrm{E}_{\mathrm{m}}(\mathrm{mV}) & \mathrm{E}_{\mathrm{K}}(\mathrm{mV}) &
\text { K conductance} \
&&& \text { (relative units)}
\end{array}$

Question

In an experimental preparation of a nerve axon, membrane potential $\left(\mathrm{E}_{\mathrm{m}}\right), \mathrm{K}^{+}$ equilibrium potential, and $\mathrm{K}^{+}$conductance can be measured. Which combination of values will create the largest outward current flow?

$\begin{array}{cccc} 
&  \mathrm{E}_{\mathrm{m}}(\mathrm{mV}) & \mathrm{E}_{\mathrm{K}}(\mathrm{mV})  & 
 \text { K conductance} \
&&& \text { (relative units)}
\end{array}$

Quizplus · Accepted Answer

[IV C]. Data sets A and F have no difference between membrane potential
(E
m
) and E
K and thus have no driving force or current flow; although data set F has the
higher K+ conductance, this is irrelevant since the driving force is zero. Data sets C, D, and
E all will have outward K+ current, since E
m is less negative than EK; of these, data set E will
have the largest outward K+ current because it has the highest driving force. Data set B will
have inward K+ current since E
m is more negative than EK.

In an Experimental Preparation of a Nerve Axon, Membrane Potential (Em),K+\left(\mathrm{E}_{\mathrm{m}}\right), \mathrm{K}^{+}(Em​),K+

In an Experimental Preparation of a Nerve Axon, Membrane Potential $\left(\mathrm{E}_{\mathrm{m}}\right), \mathrm{K}^{+}$