BIO304H5 Lecture Notes - Lecture 7: Sodium-Potassium Alloy, Tetrodotoxin, Repolarization
Document Summary
Depolarization is not normally possible in cell at rest. Conductance is controlled by ion channels: if channels are closed it should be 0. Rising phase open for na: conductance is increased for na because ion gates are, due to depolarization, na conductance is decreasing, because gated channels are closing. Rising phase: membrane potential is becoming positive: driving potential becomes less and less for na to enter the cell. [ ] gradient potential driving na into cell (inside cell is more negative: as interior becomes more positive the driving force of na+ becomes less. Greater permeability to na than what is at rest. Don"t open at same time as na+ The inside membrane potential will be positive and na efflux is: so na cant be responsible for re-polarizing the membrane going to happen. Repolarizing the membrane to bring it back to its negative resting potential. No driving force early on for k+