The Eye

The Eye

1. Parts Of The Eye And What Each Part Does.

   • Iris
     • Contains muslces that allow it to control the diameter of the Pupil and therefore how much light enters the eye.
   • Sclera
     • Though supporting wall of the Eye.
   • Cornea
     • Transpartent outer layer found at the front of the Eye. It refracts and bends the light into the Eye.
   • Lens
     • Focuses the light onto the Retina (which contains receptors which are sensitive to light intensity and colour).
   • Optic Nerve
     • Carries impulses from receptors on the Retina to the Brain
   • Ciliary Muscles
     • Circular ring of muscle that surrounds the Lens adjusting the diameter of the Lens.
   • Suspensory Ligaments
     • Connects the Cilary Body with the Lens keeping it in place.
   • Pupil
     • The black hole in the centre of the Eye.
   • Retina
     • Contains 2 main types of light receptors which can produce colour vision.

2. The Iris Reflex

   • For a bright light it gets detected by the eye and that triggers a relfex which makes the pupil smaller. The Cirluary Muscles in the Iris contract and the Radial Muscles Relax reducing the amount fo light entering the Eye.
   • The opposite to the bright light occurs for a dim light but instead the Radial Muslces contract and the Circular Muscles relax making the Pupil wider.

3. Focusing on Near and Far objects

   • Near objects
     • The Ciliary Muscles contract which slackens the Suspensory Ligaments. This makes the Lens go fatter increasing the amount of refracted light.
   • Far objects
     • The Ciliary Muscles relax which allows the Suspensory Ligaments to pull tight. This makes the Lens go thinner making it refract light by a smaller amount.

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