lecture_notes_04_(ta)

lecture_notes_04_(ta) - Lecture 4: Resting Potential and...

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Potentials Reading: chapter 3, section: membrane potential, pgs 78-85 (pgs 71-76, if using 3 rd edition) chapter 4, section: electrical signals, pgs 89-92 Resting Membrane Potential - This is the voltage difference that exists across the plasma membrane, expressed in millivolts , when the cell is at rest (i.e. no perturbing influences). Charge separation across a membrane creates membrane potential Charge separation across a membrane creates membrane potential ( MEMBRANE POTENTIAL ’ = VOLTAGE DIFFERENCE ( IN VS . OUT )) How does the cell create charge separation? 1. Establishes and maintains concentration gradients for key ions ( Na + , K + , A - (A- = ANIONS , INCLUDING NEGATIVELY CHARGED PROTEIN MOLECULES ) ) ( VIA N A +K+ATP ASE PUMP ) 2. Ions diffuse through the membrane down their concentration gradients. ( VIA LEAK CHANNELS , THIS IS AN ESSENTIAL STEP , IT ALLOWS CHARGE SEPARATION ) 3. Diffusion through the membrane results in charge separation, creating a membrane potential (electrical gradient ( VIA VOLTAGE DIFFERENCE ) ). 4. Net diffusion continues until the force exerted by the electrical gradient exactly balances the force exerted by the concentration gradient. Concentration gradient (Table 3-3) ( VIA N A +K+ATP ASE PUMP ( NET 1 POSITIVE CHARGE OUT PER CYCLE (2 K+ IN , 3 N A + OUT ))) Macromolecular anions (A - ) - high intracellular concentration of nucleic acids and proteins which carry a net negative ionic charge. Na
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This note was uploaded on 05/02/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.

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lecture_notes_04_(ta) - Lecture 4: Resting Potential and...

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