Which ion(s) have a net chemical force acting to move the ion(s) into the cell? (Assume a resting membrane potential (V_m) of -70mV.)

Question

Quizplus · Accepted Answer

The net chemical force acting on an ion to move into the cell depends on both the concentration gradient and the electrical gradient. For XS1U1P1+ (a positively charged ion) with a higher extracellular concentration ([ECF] = 120 mM) than intracellular concentration ([ICF] = 30 mM), the concentration gradient would drive the ion into the cell. Given the resting membrane potential is negative (-70mV), the electrical gradient also favors the movement of positive ions into the cell. For B S1U1P1- (a negatively charged ion) with a higher extracellular concentration ([ECF] = 140 mM) than intracellular concentration ([ICF] = 30 mM), the concentration gradient drives the ion into the cell. However, the negative resting membrane potential would oppose the entry of negatively charged ions, but since the concentration gradient is significantly large, it can still result in a net force moving the ion into the cell. A S1U1P1- has equal concentrations inside and outside ([ECF] = [ICF] = 100 mM), so there's no net concentration gradient driving its movement, and the electrical gradient alone is not sufficient to determine its movement without additional context. Therefore, both XS1U1P1+ and B S1U1P1- ions have a net chemical force acting to move them into the cell.

Which Ion(s) Have a Net Chemical Force Acting to Move