What is the role of photochemistry in vision?

Photochemistry plays a key role in human vision because light triggers chemical reactions in the eye that allow us to see.

How Photochemistry Works in Vision

1. Light Absorption
   • Light enters the eye and reaches the retina, which contains photoreceptor cells (rods and cones).
   • These cells contain a light-sensitive molecule called retinal.
2. Photoisomerization
   • When retinal absorbs light, it changes shape from 11-cis-retinal to all-trans-retinal.
   • This is a photochemical reaction — light energy causes a chemical change.
3. Signal Transmission
   • The shape change triggers a cascade of chemical reactions in the photoreceptor cell.
   • This sends an electrical signal to the brain via the optic nerve.
4. Image Formation
   • The brain interprets these signals as vision, allowing us to see shapes, colors, and light intensity.

Simple Summary

• Light → Retinal molecule absorbs it → Changes shape → Sends signal → Brain sees image.
• Without photochemistry, light could not be converted into a signal, and vision would not be possible.

In short: Photochemistry is essential in vision because light causes chemical changes in retinal, which start the process of seeing.