K+ and Na+ equilibrium/membrane potential

Question 1

what 2 opposing forces are acting on the K+ ion

Answer 1

conc. gradient, tend to move outwards

electrical gradient, tends to move inwards

Question 2

what is meant by the term equilibrium potential

Answer 2

when the conc. gradient and electrical gradient exactly balance each other, no net movement across membrane

Question 3

what is the equilibrium potential of K+

Answer 3

equilibrium potential for K+(Ek) = -90mV

Question 4

what equation is used to calculate the equilibrium potential of any ion

Answer 4

the Nernst equation

Eion = 61 . log10 . ([ion]out of cell / [ion]in cell)

Question 5

what are the forces acting on the Na+ ion

Answer 5

conc. gradient tends to move into cell

electrical gradient tends to move out of cell

Question 6

what is the equilibrium potential of Na+

Answer 6

ENa = +61mV

Na is subscript

Question 7

describe the relationship between the permeability of an ion and the membrane potential

Answer 7

the greater the permeability of an ion the more drive it will have to move the membrane potential towards its own equilibrium potential

Question 8

what is the charge of resting membrane potential value for all cells, and give example of nerve cell

Answer 8

always -ve charge

nerve cell = ~70mV, much closer to Ek because it is 100x more permeable than Na+

Question 9

give the name and the equation for the equation used to calculate the membrane potential

Answer 9

the Goldman-Hodgkin-Katz(GHK) equation

Em = 61 . log10 . [(Pk[K]o + Pna[Na]o)/(Pk[K]i + Pna[Na]i)]

where Pk = 1 , Pna = 0.01 , i = inwards, o = outwards