Cardiac Action Potential

The RMP (Resting membrane potential) is determined by the conductance to potassium ions. because

Basic Terminologies


It is caused by the movement of positive ions into the cardiac cell. Or inward current that brings positive charge/ions into the cell and causes depolarization of the cell membrane.


It is caused by the movement of positive ions out of the cardiac cell. Or inward current that brings positive charge/ions out the cell and causes repolarization of the cell membrane.

cardiac action potential

Phases of Cardiac Action Potential

Phase 0

cardiac action potential

It is caused by a sudden increase in sodium inflow. this results in depolarization of the membrane. At the peak of action potential, the membrane potential approaches the sodium equilibrium potential.

Phase 1

cardiac action potential

Phase 1 begins with initial repolarization. It is caused by an increased outflow of potassium ions out of the cell and decreased inflow of the sodium ion. 

Phase 2

cardiac action potential

It is the plateau of the action potential that is caused by a transient increase in calcium conductance inside the cell. During this phase, outward and inward currents are equal and thus maintains the plateau phase.

Phase 3

cardiac action potential

It is a phase of repolarization. calcium conductance is decreased in this phase and potassium conductance increases. Therefore the high potassium conductance results in large outflow of current which results in the hyperpolarization of the membrane. because

Phase 4

Phase 4 is the resting membrane potential

cardiac action potential

Medical Disclaimer:
The information provided on this website ( is only for educational purpose and is Copyrights Protected.

While we tried hard to write quality articles but still, the articles and the information within them is not guaranteed to be free of factual errors or typos and hence may not be correct. You are advised to independently verify the claims in the articles and make your own conclusion.

because of g
therefore, because,  therefore
, therefore, because yes please because
Because I know therefore I will not.
Yes because I
Yes because i know it. thank you therefore beacuseknow that cardiac action potential is caused therefore because yes.