For a membrane potential of -70 mV for a resting nerve cell, to what ratio of the concentrations

step 1 Potassium equilibrium Potential K -positive Potassium is a positively charged ion charged ions t

For a membrane potential of -70 mV for a resting nerve cell,...

For a membrane potential of $-70 \mathrm{mV}$ for a resting nerve cell, to what ratio of the concentrations of $\mathrm{K}^{+}$ inside and outside would this correspond if there was equilibrium at $25^{\circ} \mathrm{C} ?$

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Key Concepts

Nernst Equation

The Nernst equation is a fundamental relation in electrochemistry that links the equilibrium potential of an ion to the ratio of its concentrations across a membrane. It shows that the voltage difference (membrane potential) is proportional to the natural logarithm of the concentration gradient and involves physical constants such as temperature, the gas constant, and the ion’s charge.

Membrane Potential

Membrane potential refers to the electrical potential difference between the inside and the outside of a biological cell. It arises from the differential distribution of ions across the cell membrane and is essential for processes such as nerve signal transmission. An equilibrium membrane potential indicates that the driving forces for ion movement are balanced by the electrical forces.

Temperature Dependence in Electrochemical Equilibrium

Temperature affects the magnitude of the equilibrium potential calculated using the Nernst equation. At a given temperature, like 25°C, the factor (RT/F) becomes fixed, thereby determining the sensitivity of the membrane potential to changes in the concentration ratio. This temperature dependence is critical for accurately relating ion distribution to the observed membrane voltage.

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