Photoreceptors

Photoreceptors

Photoreceptors are Light Receptors in Your Eye

1. Light enters the eye through the pupil. The amount of light that enters is controlled by the muscles of the iris.
2. Light rays are focused by the lens onto the retina, which lines the inside of the eye. The retina contains photoreceptor cells – these detect light.
3. The fovea is an area of the retina where there are lots of photoreceptors.
4. Nerve impulses from the photoreceptor cells are carried from the retina to the brain by the optic nerve, which is a bundle or neurones. Where the optic nerve leaves the eye is called the blind spot – there aren’t any photoreceptor cells, so it’s not sensitive to light.

Photoreceptors Convert Light into an Electrical Impulse

1. Light enters the eye, hits the photoreceptors and is absorbed by light sensitive photo pigments. (Light goes straight through the neurones to the photoreceptors).
2. Light bleaches the pigments, causing a chemical change and altering the membrane permeability to sodium.
3. A generator potential is created and if it reaches…