I've recently learned about ion leak channels in the context of membrane potential and action potentials. Neurons have ion pumps that require energy in order to maintain the resting membrane potential and concentrations of K+ and Na+, yet the K+ and Na+ leak channels seem to directly oppose this purpose. It seems like, if left unopposed, the ions would eventually diffuse across the membrane such that there would be equal concentrations on both sides and a membrane potential of 0.
If the ion pumps spend energy and store it in an electrochemical gradient, don't leak channels let that potential energy dissipate back across the membrane? Wouldn't it be more efficient to tightly seal ions into their respective sides until the energy is released during action potential?
Am I missing:
- An important function of leak channels directly involved in maintaining membrane potential or causing action potentials?
- Some broader evolutionary purpose of leak channels that help ensure a cell's health in other ways?
Additional clarification requested: Would it be correct to say that leak channels function in facilitating changes in membrane potential (and return to "baseline") until the threshold, at which point the voltage-gated ion channels allow for a much larger influx/efflux?