NON PACEMAKER

• Non-pacemaker: RMP -90

  • Phase 0
  • Sodium ions influx (enter cells)
  • abrupt increase
  • More positive cells (depolarization)
  • Fast sodium channels opens = “Rapid Depolarization”
  • Achieves threshold = contracts atrium and ventricle
  • From -90 to +20
• Phase 1

  • “Initial Repolarization”
  • Cells slowly become negatively charged
  • Open potassium channels (slowly)
  • Positive potassium ions efflux (Moves out of the cell) = slightly negative
  • There is still sodium ions influx thus action potential thus not decrease abruptly
  • From +20 to +5
• Phase 2

  • “Plateau Phase”
  • Balance of influx and outflow of positive ions
  • Calcium ions influx (enters the cell)
  • Potassium ions efflux (moving out) is still ongoing
• Phase 3

  • Down-regulation (Abruptly)
  • “Rapid Repolarization”
  • Muscle = negatively charged (quickly)
  • Potassium ions efflux (move outside the cell) faster
  • Cell becomes more negatively charged
• Phase 4

  • “Resting Potential”
  • Back to RMP = -90