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Human eye

Notes


Term        Description/Function
Aqueous Humour    
  • A jelly-like substance located in the anterior chamber of the eye
Choroid
  • Located behind the retina and absorbs unused radiation 
Ciliary muscle
  • A ring-shaped muscle attached to the iris
  • Contraction and relaxation of the ciliary muscle controls the shape of the lens
Cornea
  • A strong clear bulge located at the front of the eye
  • Contributes to the image-forming process by refracting light entering the eye
Fovea
  • A small depression in the retina
  • The part of the retina in which high-resolution vision of fine detail is possible
Hyaloid
  • The hyaloid diaphragm divides the aqueous humour from the vitreous humour 
Iris
  • A diaphragm of variable size whose function is to adjust the size of the pupil to regulate the amount of light entering the eye
  • Iris is the coloured part of the eye 
Lens
  • A flexible unit that consists of layers of tissue enclosed in a tough capsule.
  • It is suspended from the ciliary muscles by the zonule fibres 
Optic nerve
  • The second cranial nerve and is responsible for vision 
  • Each nerve contains approximately 1 million fibres transmitting info from the rod and cone cells of the retina
Papilla    
  • Also known as the "blind spot" and is located at the position from which the optic nerve leaves the retina 
Pupil
  • The aperture through which light enters the eye.
  • Formed by the iris.
  • As the sie of iris increases, the size of the pupil decreases and vice versa
Retina
  • The "screen" on which an image is formed by light that has entered the eye via the cornea, aqueous humour, pupil, lens, then the hyaloid and finally the vitreous humour before reaching the retina
  • The retina contains photosensitive elements (called rods and cones) that convert the light they detect into nerve impulses that are then sent onto the brain along the optic nerve 
Sclera
  • A tough white sheath around the outside of the eyeball
  • "the white of the eye"
Vitreous humour
  • A jelly-like substance

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