Bioelectricity (2)

Question 1

Give the equation for the grouping of ion channels of a type into a single conductor

Answer 1

gK = N*g'K
N = no. of open K+ channel
g'K = conductance of one K+ channel

Question 2

What is the value of neuronal membrane capacitance?

Answer 2

Cs = 1μF/cm^2

Question 3

Give the equation linking capacitance and membrane SA

Answer 3

C = (Ɛ*Ɛo*A)/d
Ɛ = dielectric constant
Ɛo = permitivity of space
A = area of capacitor
d = distance between conductors

Question 4

Give the equation for rate of membrane potential change in response to current input in the rising phase

Answer 4

𐤃Vm(t) = ImR(1-e^(-t/τ))

Question 5

Give the equation for the membrane time constant

Answer 5

τ = RC

Question 6

Give the equation for how membrane potential decays moving away from current injection point

Answer 6

𐤃Vm(x) = 𐤃Voe^(-x/λ)
x = distance from injection point
𐤃Vo = change in membrane potential at injection point
λ = membrane length constant

Question 7

Give the equation for membrane length constant (λ)

Answer 7

λ = sqrt(rm/ra)

Question 8

Give the equation linking ra and Ra

Answer 8

ra = Ra*(4/πd^2)

Question 9

Give the equation linking rm and Rm

Answer 9

rm = Rm/πd

Question 10

Give an alternative equation for membrane length constant

Answer 10

λ = sqrt((dRm)/(4ra))