Biology A-Level
threshold
What threshold means in Biology A-Level, as defined for AQA, OCR.
Definitions of threshold
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Reference: AQA
The potential of about minus 55 mV that enough sodium ions must lift the inside to, so that positive feedback opens all the remaining voltage-gated sodium ion channels.
The level a generator potential must reach to trigger an action potential in a sensory neurone.
Topics that use threshold
- Nerve impulses (A-level only) (AQA A-Level)
- Neuronal communication (OCR A-Level)
Related terms
- saltatory conduction
- absolute refractory period
- All-or-nothing law and impulse frequency
- axon and dendrites
- Calcium-triggered exocytosis
- depolarisation
- differential membrane permeability
- Excitatory and inhibitory postsynaptic effects
Using threshold in the exam
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