PSL300H1 Lecture 2: Lecture 2 - Membrane Potential
Document Summary
The pump isnt fully responsible, it just creates the concentration gradients. Pore loops create the speicificity filter,, just for k (not even water) Equilibrium potential: at equilibrium, electrical work to repel outward cation diffusion equals chemical work of diffusion down conc. gradient, membrane potential at equilibrium is determined by the concentration gradient, can be calculated using nernst equation. Nernst equation: ek+ = (rt/f) ln([k+]o /[k+]i) = -90 mv. Major part is concentration ratio for outside and inside, For muscle cells like the heart where only k goes across. Na diffuses in until buildup of na+ inside repels the outer ones (which is the eqm@+60mv)(resting/steady staee potential) To signal and send an impulse, must flip the membrane potential: Action potential: na+ channels occur in high density within. Excitable" membranes ( any membrane that generates an impulse/action potential/spike: when channels are open, membrane potential surges towards eqm na+ = 60 mv (only when. This is all there is is some excitable membranes.
