PHYS224 Lecture Notes - Lecture 20: Cardiac Action Potential, Pacemaker Potential, Resting Potential
14 Feb 2018
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Document Summary
The heart is also dependent on action potentials, called cardiac action potentials, across the cell membrane of the heart. This comes from ion movement between the inside and outside of the cell. The action potentials in the heart differ from that of skeletal muscle, however. Cardiac action potentials are not initiated by nerves, but through specialized cells called pacemaker cells in the right atrium in the sinoatrial node [1]. All cardiac muscle cells are linked to each other through gap junctions, allowing the action potentials to pass among all cells [1]. Therefore, all atrial cells can contract and then ventricular cells [1]. The resting membrane potential is around -90mv meaning the inside is more negative than the outside [1]. Outside the cell, we find sodium and chloride ions, while inside the cell its mainly potassium [1]. Depolarization occurs once sodium channels open and allow na into the cell [1].
