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EYE (Vasular tunic (Choroid (Pigments absorb stray light beams to prevent…

- - - - Ciliary muscles contract
        
        ciliary body gets pulled anteriorly towards pupil and inwards
        
        ciliary zonules relax
        
        lens bulges allowing light from close up (under 6 ft) to focus on the retina
    - - ciliary muscles relax
        
        tension in ciliary zonule stretches lens flat
  - - - Dialator pupillae
        
        Contracts to increase pupil size
        
        Sympathetic control
      - Spincter pupillae
        
        parastympathetic control
        
        Contrricts to make decrease pupil size
- - - - attachment site for extrinsic eye muscles
      - maintains shape
      - protects
- - - - Maintains intraocular pressure
      - helps support eyeball internally
      - supplies nutrients and O2 to lens, cornea, and some of retina
      - carries away metabolic waste
  - - - Maintains intraocular pressure
      - Holds layers of retina together
      - Resists pulling of extrinsic eye muscles
- - - - Contains photoreceptors
        
        general structure
        
        Tall epithelial cells turned upside dopwn with their tips in the pigmented layer
        
        two segments
        
        Outer
        
        receptor region embedded in pigment layer
        
        contains photopigments
        
        each composed of 2 parts
        
        2 more items...
        
        Cones
        
        5 more items...
        
        Rods
        
        4 more items...
        
        inner
        
        connected to outer segment by a thin stalk containing a cilium
        
        contains the cell body
        
        has slender processes that end in a synaptic terminal
    - - Pigments absorb light to prevent it from scattering in the eye
      - Act as phagocytes to renew photoreceptors
      - Produce vitamin A