Definition

Noun: * A light-sensitive pigment in the retina: Visual purple is a reddish-purple, light-sensitive pigment found in the rod cells of the vertebrate retina. It is essential for vision in low-light conditions (scotopic vision). When exposed to light, it undergoes a chemical change (dissociates), initiating the process of visual perception.

Usage

• Visual purple is crucial for night vision.
• A deficiency in visual purple can lead to impaired vision in dim light.
• The chemical dissociation of visual purple by light is the first step in the visual pathway.

Advanced Usage

• Scientific Context: In biochemistry and ophthalmology, "visual purple" is the common name for the pigment rhodopsin. Its bleaching (dissociation) by light into its components, retinene (retinal) and opsin, is a fundamental concept.
  • The study focused on the regeneration rate of visual purple after exposure to bright light.

Variants and Related Words

• Rhodopsin (n): The scientific term for visual purple.
• Retinal (n): Also formerly called ; the light-absorbing component derived from vitamin A that is part of the visual purple molecule.
• Scotopsin (n): The protein component (opsin) specific to rod cells that combines with retinal to form visual purple.
• Photopigment (n): A general term for any light-sensitive pigment, such as visual purple or the pigments in cone cells.

Synonyms

• Rhodopsin
• Rod pigment

Related Terms & Concepts

• Retina: The light-sensitive layer at the back of the eye where visual purple is located.
• Rod cells / Rods: The photoreceptor cells in the retina that contain visual purple and are responsible for low-light, monochromatic vision.
• Bleaching: The process where visual purple loses its color (dissociates) upon absorbing light.
• Night blindness / Nyctalopia: A condition often associated with a deficiency in vitamin A, which is necessary for the synthesis of visual purple.

Noun

1. a red photopigment in the retinal rods of vertebrates; dissociates into retinene by light