PHYSIOL 201 Lecture Notes - Lecture 21: Cardiac Muscle, Cardiac Muscle Cell, Pulmonary Circulation
3 May 2019
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Systemic and pulmonary circulations: pump is the two ventricles. If ventricle does not fill well, it does not matter how hard it contracts, will not be able to eject enough. Cardiac pacemaker: pacemaker cells are connected to nearby non-pacemaker cardiac muscle cells by gap junctions, membranes can generate spontaneous ap. The fastest one drives the other ones by sending depolarizing current through rest of the system and the extra current arrives to av, which goes to bundle of his. If remove sa, then av, then bundle of his. V-gated k+ channels closing at this time: depolarization continues , due to opening of v-gated t-type ca2+ channels which quickly inactive, threshold reached , due to f-type and t-type currents: at threshold v-gated. K+ channel type called ik1 contributes to very negative resting potential. V- gated ca2+ channels are closed: depolarization to threshold occurs due to local current flow through gap junctions, depolarizing phase of ap occurs due to opening of v-gated.
