[B3] The Eye Flashcards
What is the role of the cornea?
The cornea refracts light into the eye.
The cornea protects the eye against infections.
What is the role of the iris?
The iris controls how much light enters the pupil.
What is the role of the lens?
The lens refracts light and focuses is onto the retina.
What is the cilary body?
It contains cilary muscles, which are attached to the suspensory ligaments which work together to alter the shape of the lens.
Whats is the retina?
The retina is light-sensitive and is covered in receptors called rods and cones which detect light.
What are rods?
They are receptors located on the retina which sense light intensity (sensitive in dim light).
They cannot sense colour.
What are cones?
Cones are sensitive to different colours, but are less sensitive in dim light.
What is the role of the optic nerve?
The optic nerve carries impulses from the receptors to the brain.
How do the cilary muscles and suspensory ligaments adapt to look at closer images?
Light rays must be refracted more, and so the cilary muscles contract, and the suspensory ligaments slacken, making the lens more curved and refract more.
How do the cilary muscles and suspensory ligaments adapt to look at further images?
Light rays do not have to refract as much to focus on the retina, and so the cilary muscles relax, tightening the suspensory ligaments which pulls the lens into a less rounded shape.
What does it mean to be long-sighted?
When you are unable to focus on nearer objects.
The lens cannot refract light enough (or the eyeball is too short), and so the image is formed behind the retina.
How is long-sightedness corrected?
Glasses or contact lenses with a convex lens. This will help converge the light more before entering the eye..
Or corneal laser surgery.
What does it mean to be short-sighted?
When you are unable to focus on distant objects.
The lens refract light too much (or the eyeball is too long), and so the image is formed infront of the retina.
How is short-sightedness corrected?
Glasses or contact lenses with a concave lens. This will disperse the light more before it enters the eye.
What is colourblindness caused by?
Cones (photoreceptors) do not respond normally to light.
