Question

Explain the mechanism of generation of light-induced impulse in the retina.

Answer 1

The retina is the photoreceptive layer of the eye and it helps in the sensation of vision. It has two types of cells, rod cell, and cone cell. Photoreceptor cells are composed of a protein called opsin and an aldehyde of vitamin A called retinal. When light rays are focused on the retina through the cornea, the retina gets dissociated from opsin. As a result, the structure of opsin gets changed. This, in turn, causes the permeability of the membrane to change, thereby generating a potential difference in the cells. Consequently, an action potential is generated in the ganglion cells and is transmitted to the visual cortex of the brain via the optic nerves. In the cortex region of the brain, the impulses are analyzed and the image is formed on the retina.