PSL300H1 Chapter 2: Chapter 2 Membrane Potentials
Document Summary
In resting state, only k+ is allowed to diffuse across freely. Na, k dependent atpase pumps na+ from inside neuron to the outside, an k+ from outside to inside. On average, 3na+ out and 2k+ in for each atp molecule used. Cl- repelled to extracellular fluid where it is concentrated. Membrane resting potential is mostly generated by the efflux of k+ down its concentration gradient. The large 2-pore family of k+ channels mediates k+ leakage. An equilibrium point is quickly reached at which the potential difference across the membrane is sufficiently strong to prevent any further net flux of k+ outside the neuron. The equilibrium potential for k+ ion is 90mv. The potential difference is expressed for the inside of the neuron relative to the outside. Nernst equation expanded to include several ionic species is goldman. At equilibrium, the inside of the membrane will be positive with respect to outside.
