PSIO 303A Lecture Notes - Lecture 33: Nernst Equation, Resting Potential, Goldman Equation
11 Nov 2016
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Block 3 - lecture 3 - nervous action. Lecture objectives: know that cytoplasmic sodium concentration is lower than the extracellular concentration, know that cytoplasmic potassium concentration is higher than the extracellular concentration. Ionic concentrations: cytoplasmic [na+] is lower than the extracellular concentration, cytoplasmic [k+] is higher than the extracellular concentration. The cytoplasm is negative which tends to pull k+ into the cell. Tends to push out k+ to the ecf. In most cells the electrical and chemical forces are balanced. The flux of k+ to the outside of the cell down its concentration gradient --> inside-negative electrical potential. Electrical potential : aka potential difference (pd, range -50 to -100 mv, an inside-negative potential of -50mv in a cell is a characteristic of cells in their resting state. Nernst equation: at equilibrium the electrical force is equal and opposite to the chemical force. The theoretical balance between electrical force and chemical force or electrical voltage and chemical gradient:
