BIO310H5 Lecture Notes - Lecture 15: Voltage-Dependent Calcium Channel, Voltage-Gated Potassium Channel, Cardiac Muscle Cell
Document Summary
So far we have 2 types of ap in the heart: pacemaker potential and myocyte potential. Types of ion channels are different than normal. The ap of cardiac myocyte is also different than normal skeletal muscle. They transfer ap thru gap junctions in the form of na+ ions to myocyte. Cardiac myocyte has resting membrane potential, unlike pacemakers. Depolarization happens due to influx of na+ sodium channels that get opened due to positive charge produced bc of na+ ions transferring thru gap junctions. The rapid gush of na+ ions will responsible for sharp depolarization. Next, ca2+ channels will open as soon as membrane potential is a bit more positive. These are voltage-gated channels that are responsible for early repolarization. Is followed by plateau phase, achieved by depolarization. It happens from the slow and prolonged opening of the voltage gated ca2+ channels. After, there will be opening of voltage gated k+ channels, resulting in repolarization phase.
