PSL201Y1 Lecture Notes - Lecture 3: Resting Potential
Document Summary
Phase i: membrane becoming more positive as more sodium coming inside cell through voltage-gated channels. As membrane becomes more depolarized, more voltage gated channels open, again allowing more sodium again. Equilibrium potential for sodium is: +60mv that"s what sodium wants the membrane to be. But mp never reaches +60 because there"s other ions involved (k) K has leaky channels and voltage gated channels (open when membrane is depolarized) voltage gated channels are voltage dependant. At +30mv (phase ii) k is driven outside due to chemical force (a lot of k inside, not a lot of k outside) and electrical force (really positive inside and negative outside) As k leaves has left due to its strong drive to leave, reach. Mp becomes really negative before dipping to resting. The reason it dips more negative than resting mp is because channels close slowly (voltage gated channels). Due to kinetics and how they affect channels.
