Physiology 3120 Lecture : Action potential

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Tom Stavraky

Document Summary

Voltage-gated sodium channels open (very rapidly), and lots of sodium flows into the cell. Membrane depolarizes rapidly to +45mv (inside of cell has positive charge), but never reaches. Potassium voltage-gated channels begin opening while sodium channels become inactivated. Little bit of overlap between channel openings: repolarization, hyperpolarization. Eventually all k channels are open & all na channels are inactivated. K continues to leave the cell (channels close slowly) Membrane potential returns to normal (-70mv), and channels return to resting configuration: voltage-gated ion channels. Reversibly binds to sodium voltage-gated channels, and prevents inactivation. Cells are in a constant state of depolarization. In the area of trabzon on the black sea: changes in sodium & potassium conductance. Sodium conductance rises very rapidly (not all sodium channels open at once [stepwise]) Potassium conductance rises after, and is more gradual (not all these channels open at once, either) Overlap of sodium & potassium conductance gives ap a rounded peak: facts about the action potential.