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Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina.A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
The function of the photoreceptor cell is to convert the light information of the photon into a form of information communicable to the nervous system and readily usable to the organism: This conversion is called signal transduction. The opsin found in the intrinsically photosensitive ganglion cells of the retina is called melanopsin.
An opsin absorbs a photon (a particle of light) and transmits a signal to the cell through a signal transduction pathway, resulting in hyper-polarization of the photoreceptor. Rods and cones differ in function. Rods are found primarily in the periphery of the retina and are used to see at low levels of light. Each human eye contains 120 million ...
The amacrine cells also introduce lateral inhibition to the axon terminal, serving various visual functions including efficient signal transduction with high signal-to-noise ratio. [ 3 ] The mechanism for producing the center of a bipolar cell's receptive field is well known: direct innervation of the photoreceptor cell above it, either through ...
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Proteins responsible for detecting stimuli are generally termed receptors , although in some cases the term sensor is used. [ 1 ]
In physiology, transduction is the translation of arriving stimulus into an action potential by a sensory receptor. It begins when stimulus changes the membrane potential of a sensory receptor . A sensory receptor converts the energy in a stimulus into an electrical signal. [ 1 ]
When the retina of the eye detects light, a reaction known as a phototransduction cascade occurs. It is a signal transduction pathway that leads to the activation of the enzyme phosphodiesterase, which hydrolyzes cGMP into 5’-GMP, decreasing the concentration of cGMP. In the absence of cGMP, the CNG channels in the photoreceptors close ...
Transducin is activated by metarhodopsin II, a conformational change in rhodopsin caused by the absorption of a photon by the rhodopsin moiety retinal. [2] [3] The light causes isomerization of retinal from 11-cis to all-trans.