PACEMAKER

• Pacemaker: RMP -60

  • Absence of Phase 1 and Phase 2
• Phase 4

  • Cells are unstable due to “Slow Depolarization”
  • Funny Sodium Channels open
  • Sodium ions influx (slow)
  • Inside of cell slowly becomes positive charge
• Phase 0

  • “Rapid Depolarization”
  • Calcium ions influx (not sodium ions) via L-Type channels (e.g. ryanodine or dihydropyridine receptors)
  • Achieves Threshold = presence of action potential = contraction
• Phase 3

  • “Rapid Repolarization”
  • Potassium ions efflux
  • Cell becomes negatively charged
  • Goes back to RMP =  -60