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Unformatted text preview: relaxation stop action potential Ca channels in plasma membrane and in SR close Ca transported out of the cell by SERCA and PMCA (plasma membrane CaATPase) Ca no longer bound to Tn, actin-myosin relax regulation of electrical and contractile activity sympathetic - norepinephrine, beta receptors, cAMP/PKA cAMP/PKA regulates: Ca channels, increase contractility (directly and CICR of RyR) shortens action potential phospholamban, which regulates SERCA, speeds relaxation and increases Ca uptake and subsequent release of Ca clinical: digitalis inhibits Na/K-ATPase and increases contractility Pacemakers regulate action potential frequency SA and AV nodes action potential and ion channels: K channels, "funny channels" and Ca channels gradual depolarization (unsteady baseline) to threshold to generate action potential regulation: sympathetic - speeds gradual depolarization parasympathetic - slows gradual depolarization...
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- Spring '09