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Flashcards in Membrane Potential Deck (3)
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1
Q
  • Electric force vs. osmotic force? Implications?
  • Two forces acting on an ion? Creates what?
  • Equilibrium potential is? Relates what? Each ion? If membrane potential = eq. potential? If they are not equal?
  • Membrane potential?
  • How to evaluate pump at steady state? (2) Same direction? Different direction? 2
  • Number of excess ions in cell?
A
  • Electric force much stronger; few ions needed to counter conc. differences
  • Conc. gradient and electric potential difference; electrochemical gradient
  • Voltage difference if a given ion was at equilibrium given ECF:ICF ratio; conc. gradient to electric force; has its own; ion is at electro-chem equilibrium; pump must exist
  • Real difference in voltage between the ECF and ICF
  • Look at [ ]i vs [ ]o to see which way it would move; look at ion charge vs. membrane potential; must be pump; compare eq. potential to mombrane potential to see if pumped or not
  • Small compared to total number of ions
2
Q
  • Bulk solutions?
  • Does cell at eq. have to have same conc. in and out? Must follow what?
  • Charge neutrality means what? Not what?
  • Nernst Eq?
  • If at steady state with no pumps?
  • Na/K pump does what?
  • Steady state def?
  • Equilibrium def?
A
  • Always neutral electrically
  • No; Donnans rule = product of ion conc. in must equal product of ion conc. out
  • # cations/anions the same in and out; inside equals outside
  • E = -60 log ( [ ]o / [ ]i )
  • -Vm = E
  • 3 Na out; 2 K in costs 1 ATP
  • Most cells; ion conc. aren’t chaning over time but energy maintains gradient
  • Ion conc. don’t change over time and don’t cost energy
3
Q
  • Driving force in cells?
  • Membrane potentials sensitive to changes in? Not to changes in?
  • Loss of NA to EC’s effect on Vm
  • Sensitivity to K+ outside cell?
  • Way to treat kyperkalemia?
A
  • Difference b/n Vm and E
  • [k+]o; [na+] o
  • Very little
  • Very; b/c starting conc. outside is so small
    C BIG K; calcium, bicarbonate, insulin, glucose, kayenolate