Membrane Potential and Action Potentials Flashcards
Ion Flux
The number of molecules that cross a unit area per unit of time ( number of particles )
Voltage ( potential difference )
Generated by ions to produce a charge gradient
Current ( amps)
Movement of ions due to a potential difference
Resistance
Barrier that prevents the movement of ions
What are changes in membrane potential caused by
Ion transporters
When is an electrochemical equilibrium achieved
When electrical force prevents further diffusion across the membrane . So when the concentration gradient exactly balances the electrical gradient .
What does the Nernst equation tell you
The equilibrium potential ( E)
What is R in the Ernst Equation
Gas constant ( 8.31)
What is T in the Ernst Equaton
Temperature in Kelvin ( 37 degrees or 310K)
What is z on the Ernst Equation
Charge on the ion ( eg. -1 for Cl - etc)
What is F in the Ernst Equation
Faradays number - charge per mol of ion
What do you do to the Ernst equation when calculating
Assume T = 37 degrees or 310 K
Convert natural log to common log
State E in mV
Male compartment 2 the inside and 1 outside
X 2 and X1 in Ernst Equation
X2 is the intracellular ion conc and X 1 is theextra cellular ion conc
Typical concentrations of sodium
150 mmol outside and 10 mmol inside
Typical concentrations of potassium
5 mmol outside and 150 mmol inside
The version of the Ernst equation we need
E = -61/z x log ( X inside /X outside )
Why do membrane potentials not rest at E k or Ena
Because there are always some channels open at all times
What does the GhK questions do
Describes the resting membrane potential ( look at the examples on OneNote )