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Intracellular potentials Extracellular Intracellular Intracellular - - PowerPoint PPT Presentation
Intracellular potentials Extracellular Intracellular Intracellular - - PowerPoint PPT Presentation
Intracellular potentials Extracellular Intracellular Intracellular microelectrotrode Replacing air with KCl in electrodes Intracellular microelectrotrode 0.1 micron Electrode resistance (10 to 30 Mohms) RC response of
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Intracellular microelectrotrode
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Replacing air with KCl in electrodes
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Intracellular microelectrotrode
0.1 micron
Electrode resistance (10 to 30 Mohms)
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RC response of electrode to current injection
Time constant?
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Electrode capacitance
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AgCl Ag+ + Cl- Ag +e-
- e- Conduction in metal
Conduction in saline solution
DC charge transfer on electrode wire
Extracellular capacitative charge transfer Intracellular direct charge transfer
Very low solubility
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Current injection into cells
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What do these have in common?
- “rubbing salt in a wound”
- Lethal injection cocktail
- Dr. Kevorkian’s suicide machine
- Hyperkalemia
- Hypokalemia
Resting Potential
O mV
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Membrane ion distributions
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Ionic basis of the resting potential
Unequal distribution of ion species across membrane
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Selective permeability of ion species through membrane Loss of K??- Q = CV 10-5 M K for -58 mV Donnan Equilibrium
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Squid giant axon- a model prep
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40,000 APs can fire!
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At Rest: INa = IK?
- IK = gK (Vm-EK) INa = gNa (Vm-ENa)
gK (Vm-EK) = gNa (Vm-ENa)
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Other contributions to RP?
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