Membrane Potentials Flashcards
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
How does voltage change cell conductance?
By opening ion channels
The Unitary Conductance of an ion channel is it’s __________________.
Open conductance
