Biology II - Special Senses Unit: Vision

vision is our ____ sense

dominant

what % of sensory receptors in out bodt are in our eyes

70%

what in our eyes converts light into action potentials that our brain can interpret

photoreceptors

how many layers are there of the eye and name them

3

fibrous (dense connective tissue), vascular (blood), inner (structure)

cornea

front portion of the fibrous layer

transparent - forms a window that lets light enter the eye

aqueous humor

clear fluid in front of the lens

pupil

opening in the center of the iris

allows light to enter the eye

iris

the colored part of the eye

made of smooth muscle layers that adjust the pupil size, allowing more or less light ti enter

vascular layer

melanin determine iris color

ciliary body

vascular layer

has muscles that change the shape of the lens, allowing it to focus

lens

hard and flattened disks

focuses incoming light directly on the retina

optic nerve

transmits action potentials to the brain

retina

inner layer

filled with photoreceptors that convert light into action potentials

2 types of photoreceptors: rods and cones

rods see low levels of light, no color

cones see high colors of light and color

choroid

vascular layer

rich in blood vessels that nourish the eye

sclera

posterior portion of the fibrous layer

white of the eye

strong - maintains the shape of the eye

vitreous humor

clear gel behind the lens that maintains the shape of the eye