The Eye

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Across
  1. 4. Mucous membrane that covers the front of the eye and lines the inside of the eyelids
  2. 7. Dark circular opening in the centre of the eye which lets light through
  3. 8. A series of fibres that hold the lens of the eye in place
  4. 10. Light-sensitive layer at the back of the eye where light energy is transduced into the electrical energy of nerve impulses
  5. 12. Transmits impulses from sensory neurones in the retina to the brain
  6. 13. Cells present in the retina that react to light, producing impulses in sensory neurones. They work well in dim light but cannot distinguish between different colours.
  7. 15. Tough outer coat of the eye
  8. 16. Circular muscles that relax or contract to enable the lens to change shape for focussing
  9. 18. Transparent layer forming the front of the eye
  10. 19. A small depression in the centre of the retina where a high concentration of cone cells can be found
  11. 20. The one area of the retina where an image cannot be formed as there are no rods or cones; this is where the optic nerve leaves the eye
Down
  1. 1. The changes that take place in the eye which allow us to see objects at different distances
  2. 2. When the pupil of the eye becomes wider e.g. in response to dim light
  3. 3. Coloured ring of tissue which controls the amount of light entering the eye by changing the size of the pupil
  4. 5. When the pupil of the eye becomes smaller e.g. in response to bright light
  5. 6. Muscles found in the iris that contract in bright light and relax in dim light
  6. 9. Muscles found in the iris that relax in bright light and contract in dim light
  7. 11. Biconvex transparent body situated behind the iris that focuses light on the retina
  8. 14. When light is bent. For example in the human eye at the air/cornea boundary and again at the lens
  9. 16. Cells present in the retina that react to light, producing impulses in sensory neurones. They work only in bright light and can respond to different colours of light - red, green and blue. They produce a sharp image.
  10. 17. Dark pigmented vascular layer which stops light being reflected around the inside of the eye