BIOL-242 Chapter Notes - Chapter 18: Electrical Conduction System Of The Heart, Pacemaker Potential, Membrane Potential
6 May 2020
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Setting the basic rhythm: the intrinsic conduction system. Ability of heart to contract does not require any nerves, however it is supplied with autonomic nerve fibers that alter the basic rhythm. This section covers how the basic rhythm is generated and modified. The activity of the heart"s in-house conduction system. Intrinsic cardiac conduction system consists of non-contractile heart cells specialized to initiate impulses. 1% of cardiac pacemaker cells have ability to depolarize spontaneously and pace the heart. Pacemakers have an unstable resting potential = pacemaker potentials. Initiate the action potentials that trigger heart contractions. 3 parts of action potential in typical pacemaker cell. Pacemaker potential // hyperpolarization at end of ap closes k + channels and opens na + channels; na + coming in = membrane becomes more positive. Depolarization // at threshold of -40mv, ca 2+ channels open, ca 2+ rushes into the cell from outside.
