What term describes the process when all sodium channels are closed even though only about 10% of rhodopsin has been bleached?

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Multiple Choice

What term describes the process when all sodium channels are closed even though only about 10% of rhodopsin has been bleached?

Explanation:
The main idea is that photoreceptors can saturate: a small amount of rhodopsin activation triggers a cascade that greatly reduces cGMP, which closes all the Na+ channels and drives the cell’s response to its maximum. Even though only a fraction of rhodopsin is bleached, the amplification in the signaling pathway pushes the rod into a saturated state where further light cannot increase the response. This differs from desensitization or adaptation, which adjust sensitivity to ongoing light, and from bleaching itself, which is simply the chemical change in the pigment.

The main idea is that photoreceptors can saturate: a small amount of rhodopsin activation triggers a cascade that greatly reduces cGMP, which closes all the Na+ channels and drives the cell’s response to its maximum. Even though only a fraction of rhodopsin is bleached, the amplification in the signaling pathway pushes the rod into a saturated state where further light cannot increase the response. This differs from desensitization or adaptation, which adjust sensitivity to ongoing light, and from bleaching itself, which is simply the chemical change in the pigment.

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