KINE 3012 Lecture Notes - Lecture 13: Cardiac Muscle, Troponin, Premature Ventricular Contraction
6 Mar 2018
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The sa node: by controlling the speed and the timing of how we generate action potentials inside it, we control heart rate, the slow rise in membrane potential is what controls heart rate. Because of that, we call it the pacemaker potential. Starting at -60, we start to see a slow rise in membrane potential, meaning that the inside of the cell is becoming more positive. This gives a closing of the potassium channels, meaning that we are holding potassium inside the cell: as membrane potential rises, you get the opening of sodium channels, increasing positive charge inside the cell further. This sodium channel is called an f-type na+ channel. The f stands for funny, and what it means is odd: right before you hit the threshold potential, you get the opening of a calcium channel called the t-type ca+ channel.
