Biology / Unit 12 Bio 2909 short lesson, about 20 seconds
Phototransduction: Rhodopsin and Hyperpolarization
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The idea
Light striking rhodopsin isomerizes its retinal component, triggering a cascade that closes sodium channels and hyperpolarizes the photoreceptor — the reverse of how most sensory neurons respond.
In practice
This hyperpolarization removes the photoreceptor's steady inhibition of bipolar cells, exciting the ganglion cells that carry signal onward.
Where people slip
Visual receptors hyperpolarize in response to their stimulus, opposite most other sensory receptors, which depolarize.
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