the transmission of chemical signals from the point of stimulus throughout the nerve fiber and function of other structures involve in the tranmission of action potential

1. Propagation of
Action potential

2. +35
RMP -90
Hyperpolarisation

3. • When the threshold level is reached
– Voltage-gated Na channels open up
– Since Na conc outside is more than the inside
– Na influx will occur
– Positive ion coming inside increases the positivity of the
membrane potential and causes depolarisation
– When it reaches +35, Na channels closes
– Then Voltage-gated K channels open up
– K efflux occurs
– Positive ion leaving the inside causes more negativity inside
the membrane
– Repolarisation occurs

4. • Since Na has come in and K has gone out
• Membrane has become negative
• But ionic distribution has become unequal
• Na/K pump restores Na and K conc slowly
– By pumping 3 Na ions outward and 2 K ions inward

6. Propagation of AP through Non
myelinated nerves
• When one area is depolarised
• A potential difference exists between that site
and the adjacent membrane

7. • This will cause opening of voltage-gated
Na channel in the adjacent membrane
• Na influx will occur
• Membrane is deloparised

8. • Then the previous area become repolarised
• This process continue to work
• Resulting in propagation of AP

9. Propagation of AP

10. Propagation of AP

11. Propagation of AP

12. Propagation of AP

13. Propagation of AP

14. Propagation of AP

15. Propagation of AP

16. Propagation of AP

17. AP propagation along myelinated
nerves
• Na channels are conc
around nodes
• Therefore depolarisation
mainly occurs at nodes

18. AP propagation along myelinated
nerves
• The current will flow one node to another
• Also, the Schwann cells acts as insulators so
they don’t allow the current to pass through it
• Thus propagation of A.P. is faster. Conduction
through myelinated fibres also faster.
• Known as Saltatory Conduction