Chemistry of Vision

Chemistry of vision: how light turns into a nerve impulse

Our vision is one of the most complex and amazing processes that occur in the human body. When looking at the world around us, light hits the retina, where it is converted into a nerve impulse, which is then transmitted to the brain for further processing. How does this happen?

Special cells on the retina called photoreceptors play a key role in vision. Photoreceptors are divided into two types: rods and cones. Rods operate in low light and provide black and white vision, while cones operate in bright light and allow color vision.

Each rod contains a light-sensitive pigment called rhodopsin. Rhodopsin is composed of retinene, an aldehyde form of vitamin A, and opsin, a protein molecule found on the surface of the rod. When light hits the rod, the retinene changes its shape, which causes the opsin to change shape and create a nerve impulse. This process is called isomerization.

Isomerization of retinene occurs very quickly and can even occur from a quantum of light, i.e. the smallest unit of light. After isomerization, rhodopsin is converted to lumyrhodopsin, which is then converted to metarhodopsin. Metarhodopsin is broken down into retinene and opsin, and the process is repeated.

One of the most interesting features of vision chemistry is that the rhodopsin system is specifically adapted for a wide range of reactions. Our eye must respond to light of very different intensities, and the rhodopsin system makes this possible.

Thus, vision is a very complex process that occurs due to chemical reactions in our body. The chemistry of vision allows us to perceive the world around us and enjoy its beauty.