The phases and action of the cardiac muscle action potential :
➖ phase 0 (depolarization) : fast-sodium channel open “AP reaches more than 20 millivolts”
➖ phase 1 (initial repolarization) : fast-sodium channels close and potassium channel open
➖ phase 2 (plateau) : calcium channels “slow one” open and potassium channels close + high permeability to calcium + low permeability to potassium
➖ phase 3 (rapid repolarization) : calcium channels close and slow-potassium channels open
+ potassium ions exit the cell
➖ phase 4 (resting potential) : -90 millivolts
➖ why the atrium function as a primer pump for the ventricle?
+ potassium ions exit the cell
