Sensory Systems Flashcards
What visible light colour has the highest frequency? Lowest?
blue, red
How much info about our environment comes from our eyes?
up to 70%
What converts light energy to biological information?
photoreceptors
Where do eyes first develop evolutionarily?
jellyfish
Do microbes have eyes?
no, but they can sense light
What are the different eye types?
simple lens eye, simple corneal eye, compound eye
What is a simple lens eye? What are some examples of things with these eyes?
single chamber with retina on one side and lens on the other
vertebrates, squid/octopus, jellyfish
What is a simple corneal eye? What is an example of things with these eyes?
no lens, light is focused only by cornea onto retina
arachnids
What is a compound eye? What are some examples of things with these eyes?
consists of many identical visual units each with own lens and receptor (like a bunch of mini eyes looking in diff directions)
insects, crustaceans
What is the cornea?
clear outer layer of eye, directs light into eyes and focuses it
What is the lens?
behind iris, focuses light on retina
What does the iris do?
controls the opening and closing of pupil
What is the ciliary muslce?
connects to and helps control iris/lens
What is the choroid?
network of blood vessels that supplys the retina, runs between retina and sclera
What is the sclera?
white outer layer of eye, maintains shape and protects from injury
What is the fovea?
small depression in center of retina where visual acuity is the highest
What is the optic disc?
where optic nerve connects to retina, blind spot (no photoreceptors)
When looking at the retina with an opthalmoscope how can you tell if its a vein or artery?
veins have wider diameters
What is the macula lutea?
surrounds the fovea, looks like a yellow ring
What are zonule fibers?
fibers that connect ciliary muslce to lens
What is accomodation?
automatic adjustment of the eye to focus
What does unaccommodated lens look like?
ciliary muslce tense and zonule fibers pull on lens to flatten it
What does accommodated lens look like?
ciliary muslce relax and lens thickens
What is emmetropia?
normal 20/20 eyes, the light is focused on the retina properly