1. Loai Alzghoul

2. Action Potential = ALL x NOTHING

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

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

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

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

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

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

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

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

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

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

13. Graded Potentials

14. Excitable cell: 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.

17. Communication Between Neurons
Electrical synapse Chemical synapse
one-way conduction, always transmits signals in one direction.
this allows signals to be directed toward specific goals.

19. 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. –
-70 mV + +
0 mV
Voltmeter + –
Dentistry 07

20. 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.