Action potentials

Action potentials

1. Length constant

   • Myelination
   • Large diameter

2. Na voltage gated channel

   • inactivation gate
     • refractory period
       • absolute
       • relative
         • stronger stimulus
   • voltage paddle - opens when repelled
   • rapid conductance
   • blocked by TTX
   • 6 transmembrane domains
   • Nav1.6

3. K voltage gated channel

   • Ca activated K channel
   • voltage paddle - opens when repelled

4. AIS

   • AP initiation
   • Increased conductance of Na
   • Increased voltage sensitivity
   • AnkG protein
     • betaIV spectrin
     • microtubule barrier
       • increased polarity

5. K channel

   • Tetramer
     • K partially hydrated
       • 4K lines up
   • alpha subunit
   • beta subunit