Vision

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Vision

• Sense organs eye
• Receptor cell photoreceptor
• Receptor signal transduction mechanism activated
  opsin membrane receptor (transducin G-protein)
  activates cGMP path to hyperpolarization in light
• Pathway of conduction photoreceptor ? bipolar
  cell? ganglion cell (as optic nerve) ? thalamus ?
  visual cortex ? visual assoc. area

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Information passes from retinal photoreceptor
cells to bipolar neurons to ganglion neurons.
(There is some convergence.)
photoreceptors
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http//www.blackwellscience.com/matthews/rhodopsin
.html
http//www.webvision.med.utah.edu/movies/trasduc.m
ov
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What effect would a decrease in phosphodiesterase
activity in photoreceptor cells have on vision?

• A decrease in phosphodiesterase activity would
  lead to a higher level of intracellular cGMP.
  This rise would, in turn, keep the gated cation
  channels open and keep the photoreceptors
  depolarized.
• This would decrease the ability of receptor
  neurons to respond to photons. And reduce the
  receipt of visual sensory information.

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Vision

• Pathway of conduction photoreceptor ? bipolar
  cell? ganglion cell (as optic nerve) ? thalamus ?
  visual cortex ? visual assoc. area

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http//www.clinicareinoso.com/conditns/refract.htm
Shortsighted or Near-sighted
Farsighted
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Eye Muscles

• Superior Oblique (IV)
• Lateral Rectus (VI)
• All others (CN III)
• Inferior Rectus
• Medial Rectus,
• Superior rectus
• Inferior Oblique
• Eye Lid Levator Palpebrae

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