Final answer:
The GHK equation describes the membrane potential based on ion concentrations and permeabilities, while the equilibrium potential is where no net ion flow occurs. The GHK equation provides a comprehensive view of membrane potential considering multiple different ions.
Step-by-step explanation:
The GHK equation quantitatively describes the membrane potential of cells in terms of the concentrations and permeabilities of different ions. The membrane potential arises due to the selective permeability of the cellular membrane to ions like sodium (Na+), potassium (K+), and chloride (Cl-). Ultimately, the GHK equation allows for the calculation of a hypothetical membrane potential based on the concentrations of various ions across the membrane and their relative permeability to the membrane. The equilibrium potential, on the other hand, is the membrane potential at which there is no net flow of a particular ion between the inside and outside of the cell. This occurs when the chemical and electrical gradients for the ion are in balance. The Nernst equation is used to calculate the equilibrium potential for a single ion type.
Overall, the GHK equation expands upon the Nernst equation, considering multiple ions to provide a more comprehensive understanding of the overall membrane potential. Using the principles of free energy and the equilibrium constant, we can also relate the membrane potential to the direction and extent to which a reaction may occur within the cell.