The eye and visual system Flashcards
visual light range
400-700 nm
what color is higher energy visable light
blue (400nm)
what color is lower energy visible light
red (700nm)
pupil
where light enters the eye
iris
controls the size of pupil/ how much light enters the eye
optic nerve
bundle of axons at the back of eye
extraocular muscles
muscles in eye that help eye focus
retnia
light receptive part of eye; contains light sensitive cells
fovea
part of retina with highest visual acuity/ most sensitive
optic disk
blind spot with no photoreceptors ; axons from ganglion cells leave the retina here to form the optic nerve
visual angle
measure size of objects in visual field
tan(theta) = S/D
what are the layers of the retnia
outer nuclear layer, inner nuclear layer, ganglion cell layer -> optic nerve
which cells in the retina can send action potentials
only ganglion cells; long distance signal sending
what are the cells in retnia
photoreceptor cells, horizontal cell, bipolar cell, amacrine cell, ganglion cells -> optic nerve
what are the 2 types of photoreceptor cells
rods and cones
rods
sensitive to light; good for night vision
cones
need more light to be active; daytime and color vision
why are photoreceptor cells light sensitive
contain light sensitive pigments
light sensitive pigments
opsins
*rods: redopsins
how do photoreceptor cells activate bipolar cells
action potential -> glutamate (excitatory)
what photoreceptor cells are in the fovea
many cones (high acuity vision) and no cones
rod pathway
provide converging input to bipolar cells to amplify visual input to ganglion cells under low light conditions
cone pathway
fovea cones may provide one to one input to bipolar cells to provide visual detail and color
convergence
amplify weak signals from photoreceptors to ganglion cells