The eye Flashcards
What is the eye and what does it contain?
- a sensory organ
- It contains receptor cells found in the retina
What is the cornea?
Receptor cells that refract (bends) light as it enters the eye
What do lenses do?
Refracts light to focus it onto the retina
What is the retina?
Contains light-sensitive receptors - Rods and Cones
What do cones do?
Detect light
(some detect red)
(others detect green or blue)
- Only work in the light
What do rods do?
Detect differences in light intensity
- Especially in the dark
What does the optic nerve?
Carry information from the eye to the brain
What does the iris do?
Adjusts the size of the pupil to allow more / less light into the eye
What does the ciliary muscle and the suspensory ligament do?
Alter the shape the lens for focussing
Where is the blind spot?
The connection of the retina and the optic nerve
What happens when light hits the retina?
It’s upside down but the brain turns it around
How is information from the eye sent to the brain?
Optic nerve by electrical impulses
What is the order of things in the eye?
- Cornea (thin layer)
- Pupil (large area)
- Iris (little sticks at the side)
- Lense (small circle)
- Suspensory ligament (lense to the ciliary muscle)
- Ciliary muscle (connected to the suspensory ligament)
What is refraction?
Light bending causing it to slow down or speed up
What controls the amount of light entering the pupil?
The muscles in the iris
which constrict or dilate
What happens when you’re short-sighted?
Distant objects appear blurry because rays of light are focused from in front of the retina
Why are some people short-sighted?
- Eyeball is too long
- Cornea is too curved so the rays of light bend more
What happens when you’re long-sighted?
Close objects appear blurry because rays of light aren’t focused from in front of the retina
What are cataracts?
Protein builds up in the eye (lenses)
How are cataracts solved?
Replacing the lenses with a plastic one
