Eye Flashcards
Cornea
Refracts light into eye
What type of organ is the eye?
Sense organ
Iris
Controls light entering pupil
Cornea
Refracts light, focus’ it onto retina - accommodation
Retina
Light sensitive part at back of eye.
Covered in receptors - rods and cones
Rods
Sensitive to dim light.
Can’t see colour
Cones
Sensitive to colour.
Not good in dim light.
Colour blindness
Caused by lack of cone cells
Optic nerve
Carries impulses from receptors to brain
Lens
Changes shape to focus
What happens when you look at distant objects?
Ciliary muscle relaxes
Suspensory ligaments pull tight
Lens thins, light is refracted less
What happens when you look at close objects?
Ciliary muscle contracts
Suspensory muscle slackens
Lens fattens and more rounded
Light is refracted more
Long sighted
Can see long distance, not close up
Lens doesn’t bend light enough or eyeball too short
Images of near objects focus behind retina
Need convex lens
Short sighted
Me! Can see near objects, not distance.
Lens bends light too much, or eyeball too long.
Image of distant objects focuses in front of retina.
Concave lens needed.
Binocular vision
2 eyes working together (humans)
Brain compares images from both eyes
More similarities, the further away object
Can judge distance well, but has narrow field of vision
