1. Events of action potential
Na+ K+
OUT
Na+ IN
A Quick Look Back
By now you should be familiar with the structure of a basic nerve cell and the events that generate the action potential at the axon hillock. The important ions that are involved in the action potential are sodium (Na+) and potassium (K+). Each of these ions has its own special voltage-gated channel that opens in response to the depolarization of the cell membrane. The Na+ channels open quickly, while the K+ channels open a little later. The movement of the ions across the membrane changes the membrane potential and produces the action potential at the axon hillock. K+

2. Nerve Physiology Membrane Potential
established by a cell membrane’s ability to alter its permeability
Defined as a charge across the cell membrane that is due to an unequal distribution of ions

3. Nerve Physiology 2 types of Membrane Potentials
Resting membrane potential
Action potential (nerve impulse)

4. axon - - - - - - - - - - - - - - - K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+
Na+ + - - -
Na+ +
Na+ - - + K+ - K+
Na+ K+ K+ - K+ K+ +
Na+ +
Fixed anions - K+ -
Na+
Na+ + +
Na+ K+ K+
Na+ -
Na+
Na+ - K+ + + K+ K+ K+ - + - + - - + + + +

5. Nerve Physiology
Action membrane potential (AP)-depolarization and repolarization constitute and AP
1. when a neuron is stimulated (in action produces nerve impulse)
2. more Na+ ions inside cell membrane
more K+ ions outside

6. Nerve Physiology Action membrane potential
3. positively (+) charged inside
negatively (-)charged on the outside
(ie Charge Reversal)
4. occurs in 2 stages
stage 1= depolarization
stage 2 = repolarization

7. Nerve Physiology Action membrane potential
Depolarization = stimulus leads to Na+ ions rushing into neuron  makes inside more positive (less negative)

8. RMP axon Depolarization of Action Potential - - - - - - - K+ K+ K+ K+
Na+ - - -
Na+ - K+ - K+ K+ K+ K+ K+ +
Na+ +
Fixed anions - K+
Na+
Na+ K+ K+
Na+ K+ + K+ K+ K+ -

9. Nerve Physiology Action membrane potential
Repolarization = occurs right after depolarization
K+ (potassium ions) rush out of neuron cell  makes inside (-) charged.

10. RMP axon Depolarization of Action Potential
Repolarization of Action Potential
axon +
Na+ - - -
Na+ - K+ - K+ +
Na+ +
Fixed anions -
Na+
Na+ K+
Na+ + K+ K+ -

11. Nerve Physiology Action membrane potential Repolarization
Sodium Potassium pump reestablishes ionic gradient for Sodium and Potassium

12. Events of action potential
Na+ K+
OUT
Na+ IN
A Quick Look Back
By now you should be familiar with the structure of a basic nerve cell and the events that generate the action potential at the axon hillock. The important ions that are involved in the action potential are sodium (Na+) and potassium (K+). Each of these ions has its own special voltage-gated channel that opens in response to the depolarization of the cell membrane. The Na+ channels open quickly, while the K+ channels open a little later. The movement of the ions across the membrane changes the membrane potential and produces the action potential at the axon hillock. K+

13. An AP can propagate itself across the surface of the PM.
The depolarization caused by the Na+ influx in one particular area of the PM causes voltage-gated channels in the adjacent membrane to open. The resulting ionic influx then causes voltage-gated channels to open in the next patch of membrane and so on and so on. Thus the AP propagates itself.