BIOL 1221 Lecture Notes - Lecture 5: Electrical Conduction System Of The Heart, Resting Potential, Pacemaker Potential
22 Jun 2017
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Length of absolute refractory period (when na+ channels are still open or inactivated): Contraction can last 15-100 ms with brief refractory periods of 1-2ms. Action potential for cardiac pacemaker cells and for contractile cardiac muscle cells. Compare the changes in membrane potential and membrane permeability that occur during each action potential. Unstimulated contractile cells of the heart maintain a stable resting membrane potential, about 1% are autorhythmic cardiac pacemaker cells that can depolarize spontaneously and pace the heart. Pacemaker cells are part of the intrinsic system, and have an unstable resting potential that constantly depolarizes (less negative) Pacemaker potential: spontaneous membrane potential changes that start an ap that spreads throughout the heart. The initiation and spread of an impulse from the. Intrinsic cardiac conduction system: noncontractile heart cells that specialize to initiate and distribute impulses throughout the heart, so that it depolarizes and contracts in an orderly manner.
