rhodopsin

n. a visual pigment associated mainly with function of the retinal rod cells. Rhodopsin consists of the vitamin A aldehyde 11-cis retinal bound to the protein opsin. When activated by light (photons), 11-cis retinal is transformed into all-trans retinal, which detaches from the opsin. This initiates a cascade of events that results in visual transduction. Also called visual purple. See scotopsin; visual cycle.

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Psychology term of the day

January 19th 2025

short-wavelength pigment

the photopigment present in one of the three populations of retinal cones that has maximum sensitivity to a wavelength of 419 nm. The absence of the gene for the short-wavelength pigment causes tritanopia, a form of color blindness in which blue and green are confused with one another. See also long-wavelength pigment; medium-wavelength pigment.