Final answer:
The light-sensitive pigment in rods is called rhodopsin, also known as visual purple.
Step-by-step explanation:
Rhodopsin is a light-sensitive pigment found in the rod cells of the retina in the eyes.
Rod cells are one of the two types of photoreceptor cells responsible for vision, particularly in low-light conditions. Rhodopsin plays a crucial role in the initial stages of the visual process.
Here's a simplified explanation of how rhodopsin works:
1. Absorption of Light: When light enters the eye and strikes the retina, it interacts with rhodopsin molecules within the rod cells.
2. Isomerization: Light absorption causes a chemical change in the structure of rhodopsin. Specifically, it leads to the isomerization of a molecule called retinal, which is part of the rhodopsin complex.
3. Signal Transmission: This chemical change triggers a series of events that result in the generation of electrical signals. These signals are then transmitted to the brain through the optic nerve.
4. Visual Perception: The brain interprets these signals as visual information, allowing us to perceive the presence of light and distinguish shapes and movement even in low-light conditions.
The term "visual purple" is often used as a colloquial name for rhodopsin due to its purple color in its unbleached state.
When rhodopsin is exposed to light, it undergoes a process called bleaching, where it loses its color. This is part of the visual adaptation process that allows the eyes to become more sensitive to low light over time.