PHGY 210 Lecture 19: PHGY 210- Lecture 19- Dr. Guevara.docx
14 May 2012
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The ventricular and atrial cells rest at a negative voltage: -90 mv. This is because at this time the membrane is only permeable to potassium. If the cell had only k+ channels, it would rest at the nernst potential, the resting potential of k+ (-100 mv). This causes k+ to move into the cell because it is negative, against its concentradient gradient. Thus the potential lies near to ek cell permeable only to potassium. The fast inward sodium current is carried by the fast inward sodium channel. A channel is a string of amino acids. Sodium channels bring graph up and potassium channels bring the graph down. review notes from phgy 1 nerves do not memorize ik1, iks, etc. A sinus node cell is never at rest pacemaker cells (unlike atrial and ventricular cells), therefore they do not have a resting potential. Voltage slowly depolarizing is called the pacemaker potential.
