Sept 24, 2013
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. A cycle. Sodium comes
inside cell very quickly.
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)
Phase II: Repolorization
But about half a millisecond after sodium volatge gated channels
open, they start closing. for that reason, MP never reaches +60mV
channel is inactivated when membrane reaches +30mV
basically a fight btw what K wants and what Na wants
after sodium channels close, K still has its leaky channels open.
K goes in. Therefore, making membrane more negative.
K has leaky channels and voltage gated chan