Depolarization - Stimulation
Sodium rushes into the cell through fast sodium channeels. Calcium moves into the cells slowly.
- -Causes the inside of the cell to become more positive.
- -Contraction begins from the innermost layer (endocardium) to the outermost layer (epicardium).
Depolarization is an electrical event expected to result in contraction, which is mechanical output, PEA is electrical without output.