BIOL 361 Lecture Notes - Lecture 2: Electrochemical Gradient, Nernst Equation, Reference Electrode
Document Summary
Na+/k+ atp pump: per each atp: pumps out 3 na, pumps 2 k+ in, creates electrochemical gradient. Electrogenic: results in a net movement of either positive or negative charges across membrane. Electroneutral: no net movement of charge ex. Explain the difference between membrane potential (em; vm) and equilibrium potential (eion; vion): Membrane potential: electrogenic transporters establish membrane potential. Cl- high outside: vm = voltage difference across membrane (membrane potential). (em) How to record vm: one electrode inside the cell, another reference electrode in the bath, potential difference as recorded on the inside of the cell. Most animals have negative membrane potential at rest. (inside slightly electronegative compared to outside. Vion/eion equilibrium potential: membrane potential when there is not net movement of ion across membrane that is permeable to that ion. Note: very few ions need to cross to change voltage across membrane. Note: equilibrium potential (reversal potential) balance of forces acting on ion diffusive force from concentration gradient.
