Eye Flashcards
What is the Cornea?
A curved transparent disc at the front of the eye. Does most of the focusing
What is the pupil?
A circular opening whose size is controlled by the iris
What is the iris?
A ring of muscles with a hole in the middle (pupil). The iris controls how much light enters the eye
What is the lens?
This is soft, flexible and transparent. Its shape can be changed to fine tune the focusing of light onto the retina
What is the ciliary muscles?
A ring of muscles at the edge of the eye which circles the lens. When is contracts the lens gets fatter. When it releases the lens gets thinner
What is the suspensory ligaments
Strong fibres which attach the lens to the ciliary muscles
What is the retina?
Contains the light sensitive cells called rods and cones
What is the optic nerve?
Consists of many neurones which carry impulses from the retina to the brain
What is the fovea
The region of the retina with the greatest number of cones
What is the conjunctiva?
A mucous membrane that covers the eye to prevent infection
What happens in dim light?
- The radial muscles contract and circular muscles relax
- The pupil dialates
What happens in bright light?
- The radial muscles relax and circular muscles contract
- The pupil constricts
What happens when focusing on an object far away?
- Ciliary muscles relax
- Suspensory ligaments are pulled tight
- Lens becomes thin and less convex
Therefore less light refraction
What happens when focusing of an object close up?
- Ciliary muscles contract
- Suspensory ligaments become slack
- Lens becomes thicker and more convex
Therefore more light refraction