eyes

• what is a lens?

  clear disc

  
• what is the lens used for?

  fine tunes the focusing of the light rays, changing their direction of the light rays to produce a clear image on the retina

  
• what are the suspensory ligaments and ciliary muscles used for?

  holding the lens in place

  
• what is the virtuous humour

  thick transparent jelly that fills the eyeball

  
• why is the virtuous humour important?

  it maintains the spherical shape of the eyeball

  
• what is the retina?

  light sensitive layer that contains cells which are stimulated

  
• what is the role of the optic nerve ?

  it has impulses that are sent along the sensory neuron, when the brain receives these messages it interprets them as visual image that is seen

  
• where is the fovea or blind spot ?

  the point where the optic nerve leaves the eye

  
• what is the sclera ?

  the white outer layer of the eye

  
• why is the sclera important?

  it is tough and strong making it hard to damage

  
• what does the cornea do?

  it allows light in the eye

  
• what is the cornea?

  the transparent area at the front of the eyeball
• the cornea has a curved surface that

  allows the light rays coming to the eye to change direction so that they are focused at the retina

  
• what is the role of the iris?

  it controls the shape of the pupil

  
• what is the iris made of ?

  muscles that contract and relax to change the shape of the pupil

  
• what is the role of the pupil?

  controls the amount of light entering the eye

  
• in bright light the pupil is small

  to reduce the amount of light entering the retina preventing damage

  
• these are structures

  inside the eye

  A) cornea

  B) pupil

  C) iris

  D) ciliary muscle

  E) suspensory ligaments

  F) lens

  G) retina

  H) fovea

  I) optic nerve