All-or-nothing Principle & the Refractory Period (AQA A-Level Biology): Flashcards
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Practise the cards
10 cards from this deck
All-or-nothing principle
All-or-nothing principle
Nerve impulses as complete responses, not variable
Threshold value
Threshold value
Minimum stimulus intensity to trigger action potential
Stimulus below threshold
Stimulus below threshold
No action potential; no nerve impulse travels
Action potential size in one neurone
Action potential size in one neurone
All identical in size and strength (same magnitude)
Frequency coding
Frequency coding
Stronger stimuli generate more action potentials per time
Recruitment method
Recruitment method
Stronger stimuli activate more neurones with higher thresholds
Refractory period
Refractory period
Recovery phase when neurone is unresponsive after action potential
Refractory period mechanism
Refractory period mechanism
Voltage-gated sodium channels closed; no new action potential possible
Refractory period & unidirectional travel
Refractory period & unidirectional travel
Region behind impulse unresponsive, prevents backward travel
Refractory period & frequency limit
Refractory period & frequency limit
Sets upper limit on action potential generation rate