single channel current ww/whA 5pA 20ms
single channel current
1. IONIC EQUILIBRIA Concentration force A B I M ++++++ 0.]M
1. IONIC EQUILIBRIA Concentration force Electrical force
Electrochemical Equilibrium When the force caused by the concentration difference and the force caused by the electrical potential difference are equal and opposite, no net movement of the ion occurs, and the ion is said to be in electrochemical equilibrium across the membrane o When an ion is in electrochemical equilibrium, the electrochemical potential difference is called as equilibrium potential or Nernst potential
Electrochemical Equilibrium • When the force caused by the concentration difference and the force caused by the electrical potential difference are equal and opposite, no net movement of the ion occurs, and the ion is said to be in electrochemical equilibrium across the membrane. • When an ion is in electrochemical equilibrium, the electrochemical potential difference is called as equilibrium potential or Nernst potential
The Nernst Equation RT TI ZF LXIB Where Ex equilibrium potential of X R ideal gas constant T absolute temperature charge number of the ion F Faraday's number Xl natural logarithm of concentration ration [X lOof X+ on the two sides of the membrane
The Nernst Equation B A X A B X X zF RT E E E [ ] [ ] ln + + = − = − Where EX equilibrium potential of X+ R ideal gas constant T absolute temperature z charge number of the ion F Faraday’s number natural logarithm of concentration ration of X+ B on the two sides of the membrane A X X [ ] [ ] ln + +
At any membrane potential other than the ex, there will be an electrochemical driving force for the movement of X+ across the membrane, which tend to pull the membrane potential toward its Ex The greater the difference between the membrane potential and the Ex will result in a greater driving force for net movement of ions Movement can only happen if there are open channels
• At any membrane potential other than the Ex , there will be an electrochemical driving force for the movement of X+ across the membrane, which tend to pull the membrane potential toward its EX . • The greater the difference between the membrane potential and the EX will result in a greater driving force for net movement of ions. • Movement can only happen if there are open channels!