Excitable Cell Physiology

  1. The Action Potential
    1. General Characteristics
      1. Threshold Potential
        1. Definition and Typical Values
          1. Determinants of Threshold
            1. Threshold Variability
            2. All-or-None Principle
              1. Binary Nature of Firing
                1. Threshold Concept
                  1. Amplitude Independence
                  2. Stereotyped Waveform
                    1. Consistency in Shape
                      1. Duration Characteristics
                        1. Cell Type Variations
                        2. Propagation without Decrement
                          1. Self-Regenerating Nature
                            1. Active Propagation
                              1. Amplitude Maintenance
                            2. Voltage-Gated Ion Channels
                              1. Voltage-Gated Sodium Channels
                                1. Channel Structure
                                  1. Alpha Subunit
                                    1. Beta Subunits
                                      1. Pore-Forming Region
                                      2. Voltage Sensing
                                        1. S4 Segment
                                          1. Gating Charges
                                            1. Voltage Dependence
                                            2. Gating Mechanisms
                                              1. Activation Gate
                                                1. Inactivation Gate
                                                  1. State Transitions
                                                  2. Kinetics
                                                    1. Activation Time Course
                                                      1. Inactivation Time Course
                                                        1. Recovery from Inactivation
                                                        2. Pharmacology
                                                          1. Tetrodotoxin Sensitivity
                                                            1. Local Anesthetic Binding
                                                          2. Voltage-Gated Potassium Channels
                                                            1. Channel Structure
                                                              1. Tetramer Formation
                                                                1. Pore Region
                                                                  1. Voltage Sensor
                                                                  2. Gating Mechanisms
                                                                    1. Delayed Activation
                                                                      1. N-type and C-type Inactivation
                                                                      2. Channel Subtypes
                                                                        1. Delayed Rectifier Channels
                                                                          1. A-type Channels
                                                                            1. Calcium-Activated Channels
                                                                            2. Kinetics
                                                                              1. Activation Time Course
                                                                                1. Deactivation Kinetics
                                                                              2. Voltage-Gated Calcium Channels
                                                                                1. Channel Types
                                                                                  1. L-type Channels
                                                                                    1. N-type Channels
                                                                                      1. P/Q-type Channels
                                                                                        1. R-type Channels
                                                                                          1. T-type Channels
                                                                                          2. Physiological Roles
                                                                                            1. Action Potential Shape
                                                                                              1. Neurotransmitter Release
                                                                                                1. Excitation-Contraction Coupling
                                                                                            2. Phases of the Action Potential
                                                                                              1. Resting State
                                                                                                1. Baseline Ion Permeabilities
                                                                                                  1. Steady-State Conditions
                                                                                                    1. Channel Availability
                                                                                                    2. Depolarization Phase
                                                                                                      1. Sodium Channel Activation
                                                                                                        1. Positive Feedback Loop
                                                                                                          1. Rapid Sodium Influx
                                                                                                            1. Membrane Potential Changes
                                                                                                            2. Peak and Overshoot
                                                                                                              1. Maximum Depolarization
                                                                                                                1. Approach to Sodium Equilibrium
                                                                                                                  1. Sodium Channel Inactivation Onset
                                                                                                                  2. Repolarization Phase
                                                                                                                    1. Sodium Channel Inactivation
                                                                                                                      1. Potassium Channel Activation
                                                                                                                        1. Potassium Efflux
                                                                                                                          1. Return Toward Resting Potential
                                                                                                                          2. Afterhyperpolarization
                                                                                                                            1. Prolonged Potassium Conductance
                                                                                                                              1. Undershoot Below Resting Potential
                                                                                                                                1. Gradual Return to Rest
                                                                                                                              2. Refractory Periods
                                                                                                                                1. Absolute Refractory Period
                                                                                                                                  1. Sodium Channel Inactivation
                                                                                                                                    1. Inability to Generate Action Potential
                                                                                                                                      1. Duration and Determinants
                                                                                                                                        1. Functional Consequences
                                                                                                                                          1. Maximum Firing Frequency
                                                                                                                                            1. Unidirectional Propagation
                                                                                                                                          2. Relative Refractory Period
                                                                                                                                            1. Partial Sodium Channel Recovery
                                                                                                                                              1. Elevated Threshold
                                                                                                                                                1. Reduced Action Potential Amplitude
                                                                                                                                                  1. Functional Consequences
                                                                                                                                                    1. Frequency Adaptation
                                                                                                                                                      1. Stimulus Strength Encoding
                                                                                                                                                  2. Action Potential Initiation
                                                                                                                                                    1. Axon Hillock
                                                                                                                                                      1. Low Threshold Region
                                                                                                                                                        1. High Sodium Channel Density
                                                                                                                                                          1. Integration Zone
                                                                                                                                                          2. Threshold Mechanisms
                                                                                                                                                            1. Critical Depolarization Level
                                                                                                                                                              1. Sodium Channel Activation
                                                                                                                                                                1. Positive Feedback Initiation
                                                                                                                                                              2. The Voltage Clamp Technique
                                                                                                                                                                1. Principles and Methodology
                                                                                                                                                                  1. Membrane Potential Control
                                                                                                                                                                    1. Current Measurement
                                                                                                                                                                      1. Feedback Amplifier
                                                                                                                                                                      2. Ionic Current Separation
                                                                                                                                                                        1. Pharmacological Isolation
                                                                                                                                                                          1. Ion Substitution
                                                                                                                                                                            1. Subtraction Methods
                                                                                                                                                                            2. Hodgkin-Huxley Analysis
                                                                                                                                                                              1. Conductance Measurements
                                                                                                                                                                                1. Kinetic Modeling
                                                                                                                                                                                  1. Mathematical Description

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                                                                                                                                                                              3. Passive Electrical Properties and Graded Potentials

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                                                                                                                                                                              5. Propagation of the Action Potential