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Cardiac Action Potentials definitions

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  • Pacemaker cells
    Heart cells that set the rhythm through autorhythmicity, initiating action potentials without external signals.
  • Contractile cells
    Heart cells responsible for contraction and blood pumping, experiencing rapid depolarization and a plateau phase.
  • Depolarization
    A phase where the cell's membrane potential becomes less negative, often due to sodium or calcium ion inflow.
  • Repolarization
    The process of restoring the cell's membrane potential to a negative value after depolarization.
  • Plateau phase
    A phase in cardiac action potentials where depolarization is prolonged due to calcium inflow and potassium outflow.
  • Autorhythmicity
    The ability of pacemaker cells to generate action potentials independently, setting the heart's rhythm.
  • Sodium ions
    Positively charged ions that contribute to depolarization by entering the cell.
  • Calcium ions
    Positively charged ions that prolong depolarization in cardiac cells by entering the cell.
  • Potassium ions
    Positively charged ions that contribute to repolarization by exiting the cell.
  • Absolute refractory period
    A period during which cardiac cells cannot respond to new action potentials, ensuring relaxation.
  • Pacemaker potential
    The slow depolarization phase in pacemaker cells that initiates action potentials.
  • Intrinsic cardiac conduction system
    The system responsible for initiating and spreading action potentials throughout the heart.
  • Gap junctions
    Channels that allow action potentials to pass directly from one cardiac cell to another.
  • Millivolts
    A unit of measurement for electrical potential used to describe changes in membrane potential.
  • Resting potential
    The stable, negative membrane potential of a cell when it is not being stimulated.