THE EYE Flashcards
What are the components of the eye?
Cornea - refracts light into the eye
Pupil - lets light into the eye; changes in size depending on the surroundings’ brightness
Retina - where cells, rods and cones are found
Optic nerve - transfers retina’s image to the brain
Fovea - light is focused here, part of the retina where cone cells are concentrated
Cilliary muscle - contract/relax to change the lens shape when looking at objects from close/far away
Suspensory ligaments - attaches lens to the cillary muscles
Lens - focuses light on the retina
Iris - circular muscle; controls size of the pupil
Choroid layer - full of blood vessels, exchanges nutrients and waste in and out of the eye
Sclera - tough protective layer around the eye
How does the eye change with light levels?
In bright conditions, the circular muscles in the iris contracts and the pupil shrinks so less light gets in - very bright light damages the retina
In dim conditions, the radial muscles contract and the pupil increases in size to let more light in
How does the light change with distance?
When looking at distant objects, the cillary muscles relax, contracting the suspensory ligaments, making the lens less convex, thinning out, so light refracts by smaller amounts
When looking at close-up objects, cillary muscles contract, relaxing suspensory ligaments, making lens more convex, increasing the amount of refraction of light
What are the types of receptors in the eye?
Rods - black and white, see best in dark conditions
Cones, colour, see best in light
