NPB 113 Lecture Notes - Lecture 4: Hcn Channel, Resting Potential, Electrical Resistivity And Conductivity
3 Apr 2021
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Auto rhythmic cells ( pacemaker cells , conductive cells ) spontaneously depolarize and exhibit pacemaker aps. Sinoatrial ( sa) node : primary pacemaker. - - - - - - - - - - threshold. Phase 4 : spontaneous , slow depolarization. " kt efflux ( ik - slow ) shuts down no more repolarization. Hcn - channel : activated by hyperpolarization during phase 3 nat influx depolarization. T- type cast channel ( ica - t) activated by depolarization. " cah influx further depolarization to threshold. Nat 13 cart exchanger contributes to depolarization in:s:c: Activation of v - gated l- type ca"t channel ( ica - l) Peak : deactivation of l- type ca" channel ( no more ica - l) " kt efflux mainly through ik- slow ( but also ik- rapid ) repolarization. " rule 1 : atria contract before the ventricles. : rule 2 : cardiac myocytes all contract as a coordinated unit node.
