NPB 100 Lecture 3

NPB 100 Lecture 3 - Lecture 3 -membrane allows develop...

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Lecture 3 -membrane allows develop difference concentration of ion inside and outside of the cell -thus leading to development of membrane potential -the membrane selectively permeable to potassium ions for low membrane potentials -membrane current proportional to some membrane conductance times the membrane potential -Na hypothesis: permeability of sodium sensitive to Em -action potential: resistance must have changed -some selective change in permeability in response to depolarization (if you change the Em enough) -depolarization leads to the increase in conductance for Na -increasing Na current, increasing flux of Na into the cell -causes more depolarization taking it up to equilibrium potential for Na -depolarization must also cause an increase in K conductance -will increase K current, K leaves the cell (negative feedback loop) -permeabilities are always relative to one another -inward current is going more negative -in response to changing Em from -65mV to -9mV -see an inward current that changes to an outward current -assume that only K and Na present -use Na free seawater -subtract the current recording from that of normal seawater
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-results in the Na current recording -sodium current activated more quickly -potassium stays on as long as cell is depolarized -sodium current doesn’t, it turns off after awhile -sodium current inactivation -activation and inactivation, the kinetics, of the two currents are different
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This note was uploaded on 03/15/2010 for the course NPB NPB taught by Professor Bales during the Winter '09 term at UC Davis.

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NPB 100 Lecture 3 - Lecture 3 -membrane allows develop...

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