Factors that maintain a Resting Membrane Potential 2023/2024 passed

Factors that maintain a Resting Membrane Potential Resting Membrane Potential: - correct answer Exists because of a small buildup of negative ions in the cytosol alone the inside of the membrane, and an equal buildup of positive ions in the extracellular fluid alone the outside surface of the membrane. Factor #1 - correct answer *Unequal distribution of ions in the ECF and cytosol. Extracellular fluid is rich in Na+ and Cl- Cytosol- main cation is K+ -Plasma membrane typically has more K+ leak channels than Na+ leak channels, the number of K+ ions that diffuse down their concentration gradient out of the ECF into the cell. As more and more positive P+ ions exit, the inside of the membrane becomes increasingly negative, and the outside of the membrane becomes increasingly positive. Factor #2 - correct answer *Inability of most anions to leave the cell Contributes the the inside-negative resting membrane potential: Most anions inside the cell are not free to leave -They cannot follow the K+ out of the cell cause they are attached to molecules (ATP/ large proteins) Factor #3 - correct answer *Electrogenic nature of the Na+/K+ ATPhase Membrane permeability to Na+ is very slow b/c there are only a few Na+ leak channels. Nevertheless, Na+ ions slowly diffuse down their concentration gradient. Left unchecked, such inward leakage of Na+ would eventually destroy the resting membrane potential. The small inward Na+ leak and outward leak of K+ are offset by the Na+/K+ ATPhases (sodium-potassium pump) Pumps help maintain RMP by pumping out NA+ as fast as it leaks back in. At the same time the ATPhases bring in K+