Zusammenfassung der Ressource
Action Potentials
- Large, brief reversal of potential in axonal plasma membrane
- Initiated by stimulus, 3 factors
- Depolarisation
- Large concentration of Na+ ions cross plasma membrane
- Once threshold reached (~-50mV)
- Voltage-sensitive Na+ channels open
allowing more Na+ to rush into cell
- Produces large shift in polarity of neuron
- Now an all or nothing response
- Repolarisation
- Once polarity reaches peak (~30-50mV)
- Na+ channels are inactivated
- K+ moves out of cell to repolarise it
- Repolarise: Return to resting potential
- Hyperpolarisation
- Voltage of membrane reverses again
- Goes slightly below resting
potential (~-80mV)
- Returns to resting baseline