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