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Comparative Vertebrate Physiology

Comparative Vertebrate Physiology. Action potentials. Neuron anatomy and signaling. Action potential. Depolarization Repolarization Hyperpolarization. Action potential. Phases Resting membrane potential Depolarization Repolarization Hyperpolarization. Nernst equation.

wesley-adams
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Comparative Vertebrate Physiology

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  1. Comparative Vertebrate Physiology Action potentials

  2. Neuron anatomy and signaling

  3. Action potential Depolarization Repolarization Hyperpolarization

  4. Action potential • Phases • Resting membrane potential • Depolarization • Repolarization • Hyperpolarization

  5. Nernst equation • Measures equilibrium potential • Depends on: • absolute temperature • valence • ratio of concentration gradients

  6. Nernst equation If [K]o = 0.01M and [K]I = 0.1M

  7. Action potential • Hodgkin and Huxley theory • Resting membrane potential

  8. Action potential • Resting membrane potential

  9. Action potential • Hodgkin and Huxley theory • Depolarization: rising phase Na+ (5,000x)

  10. Action potential • Hodgkin and Huxley theory • Repolarization : falling phase K+ (10x)

  11. Action potential • Hodgkin and Huxley theory • Hyperpolarization

  12. Membrane permeability

  13. Protein gates • Types • Chemical • Occur between neurons • Voltage • Occur within neurons

  14. Voltage gates

  15. Refractory period • Absolute • Na+ activation gate open • Relative • Na+ activation gate closed

  16. Channel toxins • TTX (tetradotoxin) • Japanese puffer fish • decreases Na+conductance • increases K+conductance

  17. Channel toxins • TEA (tetraethylammonium) • Synthetic organic compound • increases Na+conductance • decreases K+conductance

  18. Channel toxins

  19. Threshold • An all-or-none event

  20. Threshold • Factors effecting • Magnitude • Duration

  21. Excitation curve

  22. Impulse conduction

  23. Impulse conduction • Schwann cell secrete myelin

  24. Conduction velocity • Mylenated: 15 - 40 msec-1 • Unmylenated: 0.4 - 0.5 msec-1

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