Mapa mental
Action Potentials
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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
- Produces large shift in polarity of neuron
- Voltage-sensitive Na+ channels open allowing more Na+ to rush into cell
- Once threshold reached (~-50mV)
- Large concentration of Na+ ions cross plasma membrane
- Repolarisation
- Once polarity reaches peak (~30-50mV)
- Na+ channels are inactivated
- K+ moves out of cell to repolarise it
- Repolarise: Return to resting potential
- K+ moves out of cell to repolarise it
- Na+ channels are inactivated
- Once polarity reaches peak (~30-50mV)
- Hyperpolarisation
- Voltage of membrane reverses again
- Goes slightly below resting potential (~-80mV)
- Returns to resting baseline
- Goes slightly below resting potential (~-80mV)
- Voltage of membrane reverses again
- Depolarisation