Dr. Woodley is trying to explain the concepts of restingmembrane potential, equilibrium potential, and membrane potentialto the students in her laboratory. To do this, she uses a dish ofcultured motor neurons so that she can alter the solution coveringthe cells and she can use a recording electrode to pierce one ofthe cells and determine its membrane potential relative to theextracellular fluid. She asks you a number of questions before andafter she alters the conditions around the cell. Thenormal media (fluid covering the cells) contains: 145 mEq/LNa⁺        5mEq/LK⁺                 and2 mEq/L Ca⁺⁺

and the intracellular fluid contains:

15 mEq/LNa⁺          155mEq/LK⁺               and0.0001 mEq/L Ca⁺⁺(12)

1. List the factors that normally account for resting membranepotential. (3)

2. Dr. Woodley then measures the resting membrane potential(RMP) of the motor neurons and monitor that graphically displaysthe charge indicates that it is -90 mV. What does this tell youabout the influence of the ions listed above on RMP? Why would thisoccur? (3)

She then changes the media so that the new media is stillisotonic to the previous media, but it now contains 110 mEq/LNa⁺, 5 mEq/L K⁺, and 27 mEq/LCa⁺⁺and she asks you the following questions:

3. Has the equilibrium potential changed for any of the ions? Ifso, which ones changed, and which one did not?(3)

4. Given the changes made to the media, would the restingmembrane potential of the cell change? Why? Or why not?(2)