The minimum strength of stimulus needed to generate an action potential in a neuron is called the
Correct answer: B. threshold
- A. refractory value
- B. threshold
- C. resting potential
- D. summit potential
Explanation
A stimulus below threshold opens too few sodium channels to trigger the positive feedback of depolarisation, so nothing happens; at threshold, a full impulse fires. This is the basis of the all or none behaviour of the neuron.
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About Receptors
Receptors are specialized cells or proteins that detect stimuli such as light, sound, pressure, temperature and chemicals, then initiate responses through sensory or hormonal pathways. Questions distinguish sensory receptors from effectors, compare receptor types, and examine stimulus conversion into nerve impulses, including the roles of rods, cones, chemoreceptors and mechanoreceptors.
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