5.4 - Eyes (Structure)

Cards (12)

  • Cornea:
    • Transparent
    • No blood vessels (to get the oxygen it needs, oxygen has to diffuse through the cornea)
    • Refracts light slightly
  • Iris:
    • Coloured bit of eye
    • Controls how big or small the pupil is
  • Pupil:
    • gap in the middle of the iris
    • allows light to pass through to the lens
  • Lens:
    • refracts light
    • can change its shape so light focuses on the retina
  • Retina:
    • made up of two receptor cells - cone cells (colour, don’t work in low light) and rod cells (sensitive, only see black and white)
  • Fovea:
    • only cone cells
    • try to focus light on it as it is clearest
  • Optic Nerve:
    • takes impulses generated by receptor cells to the brain to be interpreted
  • Iris Reflex:
    1. Bright Light - Constricted (contracted circular muscles, relaxed radial muscles)
    2. Low Light - Dilated (relaxed circular muscles, contracted radial muscles)
  • What is the cornea?
    S transparent layer at the front of the eye which refracts light
  • Which two stimuli are the receptor cells of the eye sensitive to?
    Colour
    Light intensity
  • What is the purpose of the iris reflex?
    To ensure the optimum amount of light enters the eye
  • When the eye is exposed to bright light, will the pupil constrict or dilate? 

    Constrict