Human Eye Anatomy and Function Quiz

Structure of the Eye

• Cornea refracts light rays into the eye
• Pupil allows light to enter the eye
• Iris controls the amount of light entering the eye using circular and radial muscles
• Blind spot does not contain photoreceptors, therefore not sensitive to light
• Optic nerve transmits impulses to the brain when photoreceptors are stimulated

Lens and Fovea

• Lens refracts light onto the retina and fine-tunes focusing by changing its curve and thickness
• Fovea contains cones but not rods

Photoreceptors

• There are two main types of photoreceptors: cones and rods
• Cones:
  • Come in three types: red, blue, and green
  • Work well only in bright light
  • Responsible for color vision and formation of sharp images
• Rods:
  • Stimulated even by very dim light
  • Enable us to see in dim light but only in black and white
  • More sensitive to light and movement than cones

Pupil Response to Increased Light Intensity

• Photoreceptors in the retina detect an increase in light intensity and are stimulated
• Sensory neurone in the optic nerve transmits nerve impulses to the brain
• Relay neurone in the brain transmits nerve impulses to the iris of the eye
• Radial muscles of the iris relax and circular muscles contract, causing the pupil to constrict
• Pupil constricts to reduce the amount of light entering the eye

Production of Focused Image

• Light rays enter the eye through the pupil
• Cornea refracts light rays into the eye
• Lens refracts light onto the retina and fine-tunes focusing by changing its curve and thickness
• Focused image is produced on the retina of the eye