Photoreceptors are Light Receptors in Your Eye
- Light enters the eye through the pupil. The amount of light that enters is controlled by the muscles of the iris.
- 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.
- The fovea is an area of the retina where there are lots of photoreceptors.
- 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
- Light enters the eye, hits the photoreceptors and is absorbed by light sensitive photo pigments. (Light goes straight through the neurones to the photoreceptors).
- Light bleaches the pigments, causing a chemical change and altering the membrane permeability to sodium.
- A generator potential is created and if it reaches…