<prompt> What isare effect on membrane when extracellular concentration of K is decreased?Magnitude of RMPNegativity of the membraneMagnitude of RMPNegativity of membrane  <response>: Active Transpo of Sodium and Potassium Ions Through the Membrane--The Sodium-Potassium Na-K Pump. First, let us recall from Chapter 4 that all cell membranes of the body have a powerful Na-K pump that continually transpos sodium ions to the out- side of the cell and potassium ions to the inside, as illus- trated on the left-hand side in Figure 5-4. Fuher, note that this is an electrogenic pump because more positive charges are pumped to the outside than to the inside three Na ions to the outside for each two K ions to the inside, leaving a net deficit of positive ions on the inside; this causes a negative potential inside the cell membrane. The Na-K pump also causes large concentration gra- dients for sodium and potassium across the resting nerve membrane. These gradients are the following: Na outside: 142 mEqL Na inside: 14 mEqL K outside: 4 mEqL K inside: 140 mEqL The ratios of these two respective ions from the inside to the outside are Na insideNa outside 0.1 K insideK outside 35.0 Leakage of Potassium Through the Nerve Membrane. The right side of Figure 5-4 shows a chan- nel protein, sometimes called a tandem pore domain, potassium channel, or potassium K leak channel, in the nerve membrane through which potassium can leak even in a resting cell. The basic structure of potassium chan- nels was described in Chapter 4 Figure 4-4. These K leak channels may also leak sodium ions slightly but are far more permeable to potassium than to sodium, normally about 100 times as permeable. As discussed later, this dif- ferential in permeability is a key factor in determining the level of the normal resting membrane potential. Ref guyton and hall textbook of medical physiology 12e p 59 