the eye

• What are the receptors in the eye sensitive to?

  Light
• What is the primary function of the eye's receptors?

  They are responsible for sight
• What are the main parts of the eye and their functions?

  1. Cornea: refracts light into the eye
  2. Iris: controls light entering the pupil
  3. Lens: refracts light onto the retina
  4. Ciliary body: alters the shape of the lens
  5. Retina: light-sensitive part with rods and cones
  6. Optic nerve: carries impulses to the brain
• What is the role of the cornea in the eye?

  It refracts light into the eye
• How does the iris function in the eye?

  It controls how much light enters the pupil
• What is the function of the lens in the eye?

  It refracts light focusing it onto the retina
• What does the ciliary body do?

  It contains muscles that alter the shape of the lens
• What are the two types of receptors in the retina?

  Rods and cones
• What is the difference between rods and cones?

  Rods are sensitive in dim light, cones detect color
• What does the optic nerve do?

  It carries impulses from the receptors to the brain
• How does the eye focus on near and distant objects?

  • Near objects: ciliary muscle contracts, slackens suspensory ligaments, lens becomes less rounded.
  • Distant objects: ciliary muscle relaxes, tightens suspensory ligaments, lens becomes more rounded.
• What happens to the ciliary muscle when focusing on close objects?

  It contracts
• What shape does the lens take when focusing on close objects?

  Less rounded
• What happens to the ciliary muscle when focusing on distant objects?

  It relaxes
• What shape does the lens take when focusing on distant objects?

  More rounded
• What are the characteristics of long-sightedness?

  • Unable to focus on near objects
  • Caused by lens shape or short eyeball
  • Images of near objects focus behind the retina
  • Corrected with convex lenses
• What are the characteristics of short-sightedness?

  • Unable to focus on distant objects
  • Caused by lens shape or long eyeball
  • Images of distant objects focus in front of the retina
  • Corrected with concave lenses
• What is an alternative to glasses or contact lenses for vision correction?

  Corneal laser surgery
• What is colour blindness and its common form?

  • Colour blindness: inability to distinguish certain colors
  • Most common form: red-green colour blindness
  • Caused by non-functioning red or green cones
• Can colour blindness be cured?

  No, it cannot be cured
• What can help colour blind people see colours more normally?

  Tinted lenses
• What is a common symptom of long-sightedness?

  Difficulty focusing on near objects