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rw11
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I am wondering how many photons must be captured by a rhodopsin molecule to energize it, and also to trigger a nerve impulse to the brain or to deeper in the eyes neural system?
Photons are packets of energy that are absorbed by the rhodopsin molecules in the retina. This absorption causes a change in the shape of the rhodopsin molecules, triggering a series of chemical reactions that lead to the activation of nerve impulses.
When photons are absorbed by the rhodopsin molecules, they cause a change in the shape of the molecule. This change leads to the activation of a protein called transducin, which in turn activates another protein called phosphodiesterase. This protein then breaks down a molecule called cGMP, which is responsible for keeping the ion channels in the retinal cells open. When cGMP levels decrease, the ion channels close, leading to a change in the electrical potential of the cell and the generation of a nerve impulse.
After being activated by photons, rhodopsin undergoes a series of changes in its structure, including the release of its attached molecule of 11-cis-retinal. This molecule is then replaced by a molecule of all-trans-retinal, which is converted back to 11-cis-retinal in a process called the visual cycle. This allows rhodopsin to continue responding to photons and triggering nerve impulses.
The nerve impulses triggered by rhodopsin are transmitted to the brain via the optic nerve. Here, the impulses are processed and interpreted by specialized cells in the visual cortex. These cells are arranged in a way that allows them to detect different aspects of the visual scene, such as color, shape, and movement, which are then combined to create a complete visual perception.
Yes, rhodopsin can be regenerated through a process called the visual cycle. This involves the conversion of all-trans-retinal back to 11-cis-retinal, which can then bind to opsin to form rhodopsin once again. This allows the retina to continue responding to photons and maintaining vision in low light conditions.