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Loai Alzghoul

Loai Alzghoul. Loai.physiology@yahoo.com. A ction P otential = ALL x NOTHING. Equilibrium potential of sodium (+60 mV). K. Na. K. K. Na. Electrotonic potential. Resting potential (-75 mV). Equilibrium potential of potassium (-95 mV). The Action Potential. - 75 mV.

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Loai Alzghoul

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  1. Loai Alzghoul Loai.physiology@yahoo.com

  2. Action Potential = ALL x NOTHING

  3. Equilibrium potential of sodium (+60 mV) K Na K K Na Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential - 75 mV Passive increase in positive charge

  4. Equilibrium potential of sodium (+60 mV) Na Na Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential - 55 mV K K K Opening of voltage-gated sodium channel threshold

  5. Equilibrium potential of sodium (+60 mV) Na Na Depolarisation due to sodium influx Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential - 40 mV K K K Opening of voltage-gated sodium channel

  6. Equilibrium potential of sodium (+60 mV) Na Na Depolarisation due to sodium influx Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential voltage-gated sodium channels turn to the inactivation phase + 50 mV K K K Inactivation of voltage-gated sodium channel

  7. Equilibrium potential of sodium (+60 mV) Na Na + 50 mV K K K Depolarisation due to sodium influx opening of voltage-gated potassium channel Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential

  8. Equilibrium potential of sodium (+60 mV) Na Na - 85 mV Repolarization due to potassium influx K K K Depolarisation due to sodium influx opening of voltage-gated potassium channel Electrotonic potential Resting potential (-75 mV) Equilibrium potential of potassium (-95 mV) The Action Potential

  9. Equilibrium potential of sodium (+60 mV) Na Na - 75 mV K K K Depolarisation due to sodium influx Electrotonic potential Resting potential (-75 mV) The Action Potential Membrane potential approaches the ENa and voltage-gated sodium channels turn to the inactivation phase repolarization dueto potassium influx closing of voltage-gated potassium channel Repolarisation dueto potassium influx Hyperpolarisingafterpotential

  10. Opening of voltage-controlled potassium channel Opening of voltage-controlled sodium channel Electrotonic potential The Action Potential Inactivation of voltage-controlled sodium channel Equilibrium potential of sodium (+60 mV) threshold Resting potential (-75 mV) Hyperpolarization due to more outflux of potassium ions Dentistry 07

  11. Action potentials: are all-or-none events +60 0 mV threshold -70 Stimulus Properties of action potentials • APs do not summate - information is coded by frequency not amplitude.

  12. mV + 60 - + 30 - 0 - - 30 - - 60 - - 90 - Electrotonic potential Localized non propagated Recording membrane potential Action potential Dentistry 07

  13. Graded Potentials

  14. Excitablecell: NEURON and MUSCLE CELL

  15. Neuron F8-2 • Axons carry information from the cell body to the axon terminals. • Axon terminals communicate with their target cells at synapses.

  16. Communication Between Neurons • Electrical synapse Chemical synapse

  17. – + + 0 mV + + + – – -70 mV + – + – – + – + – – + – + – – + + Recording of Resting and action potentials • It is recorded by cathode ray oscilloscope it is negative in polarized (resting, the membrane can be excited) state with the potential difference inside the cell membrane is negative relative to the outside. Voltmeter Dentistry 07

  18. Terminology Associated with Changes in Membrane Potential F8-7, F8-8 • Depolarization- a decrease in the potential difference between the inside and outside of the cell. • Hyperpolarization- an increase in the potential difference between the inside and outside of the cell. • Repolarization- returning to the RMP from either direction. • Overshoot- when the inside of the cell becomes +ve due to the reversal of the membrane potential polarity.

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