The Resting Membrane Potential I: Forces and Ohm's Law

Concept: Concentration Gradients and Voltages as Forces

4m

Concept: Ohm's Law

3m

Concept: Dual Nature of Ions-- Ions As Chemicals and Charges

2m

Problem: Normally, Na+ ions can’t cross cell membranes very easily, because they’re hydrophilic cations and the membrane is lipophilic. If a Na+ channel in the membrane opens and increases the permeability of the membrane to Na+, which variable in Ohm’s Law (I=Vg) is directly changed by the opening of the channel?

2m

Problem: Normally, Na+ ions can’t cross cell membranes very easily, because they’re hydrophilic cations and the membrane is lipophilic. If a Na+ channel in the membrane opens and increases the permeability of the membrane to Na+, how will that change affect the transmembrane current of Na+?

2m

Problem: A cell is sitting in a KCl solution. Outside the cell, [K+]=10 mM. Inside of the cell, [K+]=100 mM. As a result of this separation of K+, there is a transmembrane voltage V= -61 mV (i.e. the inside of the cell is more negative than the outside). Which of the following accurately describes the type(s) and direction of force(s) acting on the K+ inside of the cell? (Choose all that apply.)

4m