Physiology 2130 Lecture Notes - Lecture 4: Resting Potential, Axon Hillock, Electrochemical Gradient

• School: Western University
• Department: Physiology
• Course: Physiology 2130
• Professor: David Bell

Document Summary

Almost all cells in the body have membrane potentials. Excitable cells- nerve and muscle cells, because they use resting membrane potential to generate an electrochemical impulse action potential. Movement of k+ and na+ ions cause rapid change in potential, while they"re moving through special channels. Rapid reversal of resting membrane (-70 to +35) (depolarization). Then the membrane returns to -70 (repolarization). Then it becomes more negative briefly (-90mv) (hyperpolarization) then returns to -70mv. Found on axon, essential for generation of action potential. They are sensitive to membrane changes and open when depolarization occurs (-70 to -60: voltage gated sodium, voltage gated potassium. Na+ flow into the cell down the concentration gradient. Channel returns to rest: inactivation gates open, activation gates closed. Inactivation gates close, na+ cant flow in. channel wont open (refractory period is while gate is shut) Only for k+, has only one gate when membrane depolarizes. These channels become activated while sodium channels start to become inactivated.