8-28-09 The Membrane Potential

8-28-09 The Membrane Potential - TheMembranePotential...

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The Membrane Potential The Membrane Potential Dr. McKemy 8/28/2009
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Membrane Potential Membrane Potential The plasma membranes of excitable cells have a membrane potential . Electrical voltage difference across the membrane. Due to differences in sodium and potassium ion concentration in and out of the cell. h Potassium is higher inside cell, sodium is higher outside. Inside of the cell has a higher concentration of negative phosphate ions and proteins.
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Some basic electrical concepts Some basic electrical concepts Voltage (V) Represents the potential to do work. Can be positive or negative. h Volts, usually milli- (10 -3 ) volts Current (I) The flow of positively or negatively charged ions. Results in a movement of charge from one side of the membrane to another. h Amps, usually micro- (10 -6 ) or nano- (10 -9 ) amps Resistance (R) Something that impedes the flow of ions. h Ohms. The opposite of resistance is conductance (g). Ohms law V=IR or I = V/R = Vg
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Some basic terms Some basic terms Polarized Difference in net charge on either side of membrane. Hyperpolarized
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This note was uploaded on 04/18/2010 for the course BISC 421 at USC.

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8-28-09 The Membrane Potential - TheMembranePotential...

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