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11 Cards in this Set

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Cornea
thin transparent film coats eye

functions:
-protects the eye
-focus light (most)
Pupil
hole in eye that allows light to pass through
Iris
muscle that surrounds the pupil.

Function
1) gives eye color
2) allows pupil to change size to accommodate different levels of light
Lens
further focuses light. can change thickness to change focal length. becomes hard with age.
retina
structure at back of eye; sheet of photosensitive cells that detect light through photoreceptors - rods and cones

filled with photochemical, whose geometry changes when light detected and electrical signal given off
Transduction
when physical energy is converted to a neural signal
Retinal ganglion cells
Photoreceptors form synapses with other cells and neural signal arrives here.
Axons of ganglion cells form optic nerve.
optic disk
hole in retina with no photoreceptors --> blindspot
Rods
cylindrical shaped, can't see color. dim light. extremely sensitive to light. rhodopsin. poor acuity due to neural convergence.
Cones
cone-shaped. Three kinds of cones give ability to see color. Far less sensitive in light than rods. Much less neural convergence and thus better acuity
distribution across retina
cones - concentrated at fovea, part of retina that is hit by light from thing you are examining. drops off in periphery

rods - eventually distributed except fovea, where there are no rods.