Bioelectricity

  1. The Resting Membrane Potential
    1. Establishing Electrochemical Equilibrium
      1. The Nernst Equation
        1. Derivation and Assumptions
          1. Application to Different Ions
            1. Temperature Effects
              1. Physiological vs. Standard Conditions
              2. Calculating Equilibrium Potentials
                1. Single Ion Calculations
                  1. Example Calculations for Major Ions
                    1. Physiological Significance
                      1. Deviations from Calculated Values
                    2. Role of Ion Channels and Pumps
                      1. Potassium Leak Channels
                        1. Contribution to Resting Potential
                          1. Selectivity and Permeability
                            1. Distribution in Cell Membrane
                              1. Regulation of Channel Activity
                              2. Sodium Leak Channels
                                1. Contribution to Resting Potential
                                  1. Relative Permeability to Potassium
                                  2. The Sodium-Potassium (Na+/K+) Pump
                                    1. Structure and Function
                                      1. Stoichiometry (3Na+:2K+)
                                        1. Electrogenic Nature
                                          1. Net Charge Movement
                                            1. Contribution to Resting Potential
                                            2. Energy Requirements
                                              1. Regulation of Pump Activity
                                              2. Other Contributing Factors
                                                1. Chloride Channels
                                                  1. Calcium Pumps
                                                    1. Metabolic State Effects
                                                  2. The Goldman-Hodgkin-Katz (GHK) Equation
                                                    1. Derivation and Assumptions
                                                      1. Contribution of Multiple Ions
                                                        1. Relative Permeability of Ions
                                                          1. Weighted Average of Equilibrium Potentials
                                                          2. The Concept of Relative Permeability
                                                            1. Dynamic Changes in Permeability
                                                              1. Physiological Modulation
                                                                1. Measurement of Permeability Ratios
                                                                2. Comparison with Nernst Equation
                                                                  1. Limitations and Applications
                                                                  2. Maintaining the Steady State
                                                                    1. Balance of Passive Leaks and Active Pumping
                                                                      1. Steady-State vs. Equilibrium
                                                                        1. Role of ATP in Maintenance
                                                                          1. Energy Cost of Maintaining Gradients
                                                                          2. Consequences of Pump Failure
                                                                            1. Membrane Depolarization
                                                                              1. Cell Swelling
                                                                                1. Loss of Excitability
                                                                                2. Factors Affecting Resting Potential
                                                                                  1. Temperature
                                                                                    1. Metabolic State
                                                                                      1. Pathological Conditions

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                                                                                  1. Fundamentals of Bioelectricity

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                                                                                  3. Graded Potentials and The Action Potential