Give a brief account of: (b) Mechanism of vision
The retina is composed of three layers of cells - inner ganglion cells, middle bipolar cells, and outermost photosensitive cells. Photosensitive cells are composed of opsin and retinal. When light rays are focused on the retina through the cornea, it leads to the dissociation of retinal from opsin protein which changes the structure of opsin generating a potential difference in the cells. This action potential in the ganglionic cells and is transmitted to the visual cortex of the brain and the image is formed on the retina.
