Lecture 3 - Action potential / Nernst equation

How long is the action potential in cardiac muscles?

150-400 ms

How long is the action potential in cardiac pacemaker?

200 ms

What is a volt defined as?

1 joule of E per coulomb of charge

What is ‘F’ in ‘F coulombs’?

Faraday constant

How much charge is in 1 mole of univalent ions?

F coulombs

How much energy is needed to move 1 mole of z valent ions through a membrane potential of E volts?

zFE joules

What is the equation to find to the energy it takes to move 1 mole of substance from a conc cI (intracellular) to c0 (extracellular)?

RTln(ci/c0)

If work > 0

E is needed to move ion across membrane

If work < 0

E is released when the ion moves across the membrane

If work = 0

No E released or required - system at equilibrium

What is the E_ion ?

Equilibrium potential

What the is z value for K+?

+1

What is the z value for Na+?

+1

What is the z value for Cl- ?

-1

What is the z value for Ca2+?

+2

What is the resting membrane potential set by?

High permeability to K+ via leak channels

What happens to MP when P_Na increases?

MP become more +ve

What happens to MP when P_K increases?

MP become more -ve

What happens to MP when P_Ca increases?

MP become more +ve