A student reads that only 1/100,000 of the total K⁺ ions in…
A student reads that only 1/100,000 of the total K⁺ ions in a cell need to flow out to change the membrane potential by 100 mV. The student wonders why the concentration gradient doesn’t change significantly despite this ion movement. What explains this phenomenon? The Na⁺– K⁺ pump immediately replaces every K⁺ ion that leaves, maintaining a constant concentration Only a thin surface layer of ions (< 1 nm) near the membrane creates the potential, representing a tiny fraction of total cellular K⁺, so bulk concentration remains essentially unchanged K⁺ ions that leave are immediately replaced by Cl⁻ ions to maintain electrical neutrality The cytoplasm has buffering proteins that prevent concentration changes