BIO2A03-2011-L20 - Biol 2A03 - 2011 Lecture 20

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Biol 2A03 - 2011 Lecture 20
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
3 Basic Principles of Membrane Potentials 3.   Most membrane potentials are associated with 3 factors : (i)   Unequal distribution of ions across membranes. (ii)   An active transport mechanism which maintains/restores this unequal  distribution - e.g. Na + , K +  ATP-ase pump. (iii)   Differential permeability  of the membrane to different ions  Note for ions, the electrical analogue of permeability is  Conductance = 1/Resistance =   G 2
Background image of page 2
The Resting Membrane Potential Inside Neuron Outside Neuron 3 Na + 2 K + Electrogenic Na + /K +  -ATPases i) move  more “+” charge outside cell. ii) move K +   and Na +  against gradient to maintain  unequal distribution across membrane. -70mV RESULT: negative resting  membrane potential Na + K + G K + >> G Na +  :this means that  more K +  leaves the cell than Na +   entering the cell. This differential  K +  and Na +  leads to more “+”  charge leaving cell.   K + K + Na + Cl - Na + A - (Organic anions) 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Negative charge inside attracts  both sodium and potassium into  cell K outflow slows  down, Na  inflow speeds  up -membrane  potential  stabilizes Na/K –  ATPase  counteract s leakage  to maintain  gradients
Background image of page 4
Equilibrium Potentials and Nernst Equation (Chapter 4) predicts   the membrane potential (E M ) if the unequal ion concentrations are  fixed  & the membrane is permeable  only to the ion being considered.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

BIO2A03-2011-L20 - Biol 2A03 - 2011 Lecture 20

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online