Electrostatic potential across a cell membrane

The electrostatic potential across cell membranes plays important roles in transport and in cell signaling. Muscle contraction is stimulated by depolarization of the cell membrane. Nerve cells communicate with other cells via propagated changes in membrane potential. Also the potential across membranes of intracellular organelles, such as mitochondria, can be central components of the function of the organelles. 

In a state where the cell membrane is primarily permeable to a single ion, potassium for example, the membrane potential is primarily a function of the concentrations of that ion on either side of the membrane. If the potassium concentrations inside and outside of a cell are denoted K+, and [K+]0, respectively, and if [K+], [K+]0, then there will exist a concentration-gradient driven thermodynamic driving force quantified by  

The difference in electrostatic energy per ion between the outside and inside of the cell is given by AT/fc T, where AT is the electrostatic energy per charge. Expressing the electrostatic potential in conventional units of volts (joules per coulomb of charge), the concentration and electrostatic potential are equated in equilibrium  

If we note that the probability of finding a particle on one side of the membrane is proportional to the concentration of that side of the membrane, then we can arrive 

In living cells the potential dynamically changes as different ion transporters and channels controlled by various mechanisms open and close. Approaches to and examples of modeling cellular electrophysiology are covered in greater depth in Chapter 7. 

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Applications of thermodynamics in biology 1.7.2 Electrostatic potential across a cell membrane... 

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