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Myra Dioquino Ne Neuron Ne Neuron ons ons ~30x out ~30x in - - PowerPoint PPT Presentation
Myra Dioquino Ne Neuron Ne Neuron ons ons ~30x out ~30x in - - PowerPoint PPT Presentation
Myra Dioquino Ne Neuron Ne Neuron ons ons ~30x out ~30x in 20 000 20,000x out o t ~30x out Describes the equilibrium potential of the cell for a particular ion R Universal gas constant (8.314472 J K ) T
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Ne Neuron
- ns
Ne Neuron
- ns
~30x out ~30x in 20 000
- t
~30x out 20,000x out
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Describes the equilibrium potential of the cell for a particular ion
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R Universal gas constant (8.314472 J • K⁻¹) T
Absolute temperature (Temp. °C + 273.15 K)
z
Ionic charge (+1 for K⁺)
z Ionic charge (+1 for K ) F
Faraday constant (9.6485309 x 10⁴ C mol⁻¹)
² ²
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Nernst Equation Simulator: www.nernstgoldman.physiology.arizona.edu
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Ions flow across membrane according to
gradient “Chemical concentration vs. electrical potential” potential
An ion continues to flow until the equilibrium
potential for that ion has been reached potential for that ion has been reached
Each ion contributes to net current Each ion contributes proportionally to its rate
p p y
- f conductance
“Selective permeability”
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Why we need them:
Lipid bilayer itself doesn’t allow ion leakage across membrane
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