Action Potentials - Part 4: Myocardial Contractile Cells

Sustained or tetanic contraction of myocardial contractile cells would be life-threatening and is prevented by special properties of their action potential, leading to a significantly longer refractory period and preventing re-excitation before muscle contraction is over. The resting potential of myocardial contractile cells is around -90 millivolts. It’s almost exclusively maintained by potassium ion efflux through delayed rectifier potassium channels.

Outline:
00:00 - Introduction
00:42 - Resting potenzial
01:06 - Depolarization
01:58 - Partial repolarization
02:22 - Plateau phase
02:52 - Final repolarization
03:18 - Summary

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