The action potential

The action potential

1. RMP

   • =70mV
   • resting membrane potential
   • ICF = relative negative
   • ECF = relative positive

2. 1. Depolarization

   • Influx of Na+
     • (a)Na+ channels open & increase diffusion rate of Na+ (x800)
     • (b)raises positive charges in (-) ICF so much that it becomes positive
     • (c)Na+ diffusion rate returns to normal & K+ diffusion rate increases

3. 2. Repolarisation

   • (a)rapid efflux of K+
   • (b)outside of cell (ECF) becomes more positive

4. 3. Hyperpolarisation

   • Efflux of K+ goes too far