Vision Flashcards
simplest eye
detect light intensity and direction its coming from
ocellus in planaria
ocellus
oriented in different directions. it receives light in and orients itself until the action potentials are the same and then it backs itself out of the light
compound eye
anthropods (insects/ crustaceans)
contains several 1000 ommatida.
each detect light and good at detecting movement
rate of 330/s (human 50/s)
single lens eye
mulluscs, jellies, spiders
moves forward adn back like a camera to focus light on the retina
vertebrate eye
cornea aqueous humor pupil lens viterous humor retina
cornea
acts as an initial fixed lens
pupil
hole in center that allows light in
diameter determined by iris
lens
focuses the light onto the back of the eye
retina
made up of cells involved in photo transduction
ganglion cell layer
interneuron layer
photoreceptors
accomodations
lens changes shape to keep images in focus
hyperopia
far sighted
focal point falls behind retina
myopia
near sighted
focal point falls in front of retina
presbyopia
loss of lens accommodation ( with aging)
astigmatism
imperfectly shaped cornea
generates 2 focal points ( light scatters)
nocturnal animals
tapetum (reflective layer)
birds
vascular retina, more cones, multiple fovea
squid/octopus
retina in proper orientation
phototransduction
when light strikes photoreceptor, it releases less neurotransmitter
iris
changes diameter or pupil
aqueous humor
fluid inbetween cornea and pupil
viterous humor
fluid in the eye
fovea
depression in the retina where visual acuity is highest
rods
high sensitivity to light
slow response
one type of rod pigment
cones
low sensitivity to light
3 cones for color
fast response
