Understanding Action Potential: Ion Movements Made Simple

Understanding Action Potential: Ion Movements Made Simple

Describe with the help of diagram the lonic basis of action potential.
Answer:

Action potential:

1. Resting membrane potential
   • It occurs due to the movement of ions causing ionic imbalance across the cell
   • This imbalance is brought by
     • Sodium potassium pump
   • It actively transports Nat and K+ ions in opposite direction
   • By this pump, 3 Na+ ions are pumped out while 2 K+ ions are moved inside the cell using ATP
   • This results in more positivity outside than inside the cell
     • Selective permeability of membrane
   • Transport channels are selective for movement of specific ions
   • Channels for negatively charged substances remains closed as a result such ions remains inside the cell leading to more negativity inside than outside
2. Action potential

Similarly K+ channels opens and leads to efflux of K+ ions

Na+ channels are short lived while K+ channels remain open for longer duration

This results in efflux of more K+ ions producing more negativity inside the cell