Phototransduction: Rhodopsin and Hyperpolarization
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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.
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This hyperpolarization removes the photoreceptor's steady inhibition of bipolar cells, exciting the ganglion cells that carry signal onward.
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Visual receptors hyperpolarize in response to their stimulus, opposite most other sensory receptors, which depolarize.