PHGY 214 Lecture Notes - Lecture 24: Pacemaker Current, Pacemaker Potential, Cyclic Nucleotide
8 Dec 2017
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Week 8 lecture 3 short-lasting event where cell memb potential rapidly rises and falls back to its original level. Purkinje and ventricular cell are fast due to lots of t tubules. Be able to diff b/n aps in diff types of cells. Plateau phase due to influx in ca which is not in nerve or skeletal cells. Sa node and av node= slow response ap, want delay so atria can finish contraction and pump blood. Bundle of his and l&r branches + pukinje fibers: fast response ap, v. g. Na chan, need to be fast to spread conduction to ventricles as fast as possible. 5 phases of ap of contractile cardiac muscle cells: depol: v. g. Skeletal muscle fast-twitch fiber: refractory is short compared w time required for development of tension. Skeletal muscle can exhibit summation and tetanus (max contraction of muscle cell) Refractory period is as long as ap in cardiac muscle so no tetanus.
