Physiology 3120 Lecture Notes - Lecture 6: Goldman Equation, Gas Constant, Electrochemical Gradient
9 Dec 2017
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Inside is negative with respect to the outside: electrical potential = difference in charge between 2 parts. Present in almost all cells at rest (can vary slightly) Generated by the selective permeability of the membrane to particular ions. Concentration assuming 1kg of water in each compartment: 2 osmoles/kg: compartment a: kcl dissociates into k+ ions and cl- ions, compartment b: nacl dissociates into na+ ions and cl- ions. K+ will move down its concentration gradient from compartment a compartment b: selective permeability creates a membrane potential, compartment a will become more negative, compartment b will become more positive. This is similar to a human cell b/c most k+ is found inside the cell & the membrane is highly permeable to k+. Compartment b becomes more positive: eventually compartment b becomes so positive that k+ doesn"t want to enter, the negative charge of compartment a attracts k+ back, eventually k+ will have no net movement. 2 forces acting on k+: 1.
