Membrane Potentials Flashcards
(26 cards)
What is Valence?
The charge on an ion given as z
How do we calculate valence?
z = - [C(ion)] / [C(e-)]
C(ion) = Coulombs of ion C(e-) = Coulombs of electron
What is Faraday Constant?
F = 96485 C/mol
How do we calculate charge (q) of n moles with a valence z?
q = zFn q = charge, z = valence, F = Faraday constant, n = moles
What is Volatge?
Electrical potential abbreviated V
What is the formula for Current (i) with respect to time?
i = q/t
i = Current
q = charge
t =time
What is the Nernst Equation?
μ(x) = nRT * ln( [x]1 / [x]2 ) μ(x) = Chemical potential energy of x
How do we calculate the electrical potential energy (EPE)?
μ(e) = zFn * V
How do we calculate the Voltage using the Nernst equation and the formula for EPE?
V = - (RT/zF) * ln( [x]in/[x]out )
NOTE: this gives the answer in V not mV
What is the general resting potential for cells?
-70mV
What is the formula for capacitance?
q = CV in Faradays
What is the capacitance of a normal cells?
~ 1.3 x 10^-11 F
Electrogenic potential is created by ________________.
Active Transport
What is the Goldman equation?
V = -RT/F * ln( {Pk[K]in + PNa[Na]in + PCl[Cl] out} / {Pk[K]out + PNa[Na]out + PCl[Cl]in} ) in V not mV
What is Ve?
Equilibrium Potential
Flux is equal to?
j = i/zFA i = current, j = flux, z = valence, F = Faraday's constant and A= area
At Ve there is __________
No flow
Between 0 and Ve the ________________ will win
The Chemical Gradient will win
If we have
The Electrical Gradient will win
Current is given as the flow of __________charge into the cell. Therefore, the flow of ______ into the cell will be classed as an outward current.
Positive
Anions
What is Ohm’s law?
V = IR V= voltage, I= Current and R= Resistance
What is conductance?
Conductance (G) is how easy it is to move charge, unit is Siemens (S)
If only voltage moves an ion we can expect:
Ix = Gx * V Ix = Current of x Gx = Conductance of x
What is Unitary Conductance (g)?
The number of channels in the membrane and the proportion that are open
