Membrane Potentials

Question 1

What is Valence?

Answer 1

The charge on an ion given as z

Question 2

How do we calculate valence?

Answer 2

z = - [C(ion)] / [C(e-)]

C(ion) = Coulombs of ion
C(e-) = Coulombs of electron

Question 3

What is Faraday Constant?

Answer 3

F = 96485 C/mol

Question 4

How do we calculate charge (q) of n moles with a valence z?

Answer 4

q = zFn
q = charge, z = valence, F = Faraday constant, n = moles

Question 5

What is Volatge?

Answer 5

Electrical potential abbreviated V

Question 6

What is the formula for Current (i) with respect to time?

Answer 6

i = q/t
i = Current
q = charge
t =time

Question 7

What is the Nernst Equation?

Answer 7

μ(x) = nRT * ln( [x]1 / [x]2 )
μ(x) = Chemical potential energy of x

Question 8

How do we calculate the electrical potential energy (EPE)?

Answer 8

μ(e) = zFn * V

Question 9

How do we calculate the Voltage using the Nernst equation and the formula for EPE?

Answer 9

V = - (RT/zF) * ln( [x]in/[x]out )

NOTE: this gives the answer in V not mV

Question 10

What is the general resting potential for cells?

Answer 10

-70mV

Question 11

What is the formula for capacitance?

Answer 11

q = CV in Faradays

Question 12

What is the capacitance of a normal cells?

Answer 12

~ 1.3 x 10^-11 F

Question 13

Electrogenic potential is created by ________________.

Answer 13

Active Transport

Question 14

What is the Goldman equation?

Answer 14

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

Question 15

What is Ve?

Answer 15

Equilibrium Potential

Question 16

Flux is equal to?

Answer 16

j = i/zFA
i = current, j = flux, z = valence, F = Faraday's constant and A= area

Question 17

At Ve there is __________

Answer 17

No flow

Question 18

Between 0 and Ve the ________________ will win

Answer 18

The Chemical Gradient will win

Question 19

If we have

Answer 19

The Electrical Gradient will win

Question 20

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.

Answer 20

Positive

Anions

Question 21

What is Ohm’s law?

Answer 21

V = IR
V= voltage, I= Current and R= Resistance

Question 22

What is conductance?

Answer 22

Conductance (G) is how easy it is to move charge, unit is Siemens (S)

Question 23

If only voltage moves an ion we can expect:

Answer 23

Ix = Gx * V
Ix = Current of x
Gx = Conductance of x

Question 24

What is Unitary Conductance (g)?

Answer 24

The number of channels in the membrane and the proportion that are open

Question 25

How does voltage change cell conductance?

Answer 25

By opening ion channels

Question 26

The Unitary Conductance of an ion channel is it’s __________________.

Answer 26

Open conductance