The eye 2

ajv09c's version from 2015-04-27 01:30

Section 1

Question Answer
larger posterior cavityvitreous chamber; vitreous humor made of gelatinous mass-helps stabilize eye shape and supports retina
diabetic retinopathydevelops in diabetes mellitus; caused by blockage of normal blood vessels, growth of abnormal blood vessels in retina, blood leakage into cavity. visual acuity decreases as photoreceptors die
lens fiberscells in interior of lens; no nuclei or organelles; filled with crystalline which provide clarity and focusing power to len
cataractcondition in which lens has lost its transparency
senile cataractmost common type. consequence of the aging process
light refractionbending of light by cornea and lens
accommodationshape of lens changes to focus image on retina
astigmatismcondition where light passing through cornea and lens is not refracted properly; visual image is distorted
the closer the light sourcethe longer the focal distance
the rounder the lensthe shorter the focal distance

Section 2

Question Answer
for close visionciliary muscle contracted, lens rounded
for distant visionciliary muscle relaxed, lens flattened
light refraction of lens reverses image and creates visual acuity
visual acuityclarity of vision; normal is 20/20
emmetropianormal vision
myopianearsightedness (distant objects blurry)
hyperopiafarsightedness (near objects blurry)
presbyopiahyperopia in older people as lenses lose elasticity
in myopia the eyeballis too deep or resting curvature of the lens is too great; makes the image of distant objects projected in the front of retina
in hyperopia the eyeballis too shallow or the lens is too flat; ciliary muscle must contract to focus even a distant object on the retina; at close range lens cannot provide enough refraction to famous image.
presbyopia happens becauseolder people lose elasticity and ability to bend the lens enough

Section 3

Question Answer
visual physiology- rods respond to almost any photon, regardless of energy content
visual physiology- coneshave characteristic rings of sensitivity
anatomy of rods and cones has two segmentsouter and inner segments
outer segment of rods and conescontains visual pigments (photopigments) that absorb light energy
pigments are synthesized fromvitamin a
retinitis pigmentosamost common inherited visual problem. caused by mutation in visual pigment, results in photoreceptor cell death and blindness
inner segment of rods and conesnarrow stalk connects outer segment to inner segment
inner segment of rods and cones containsphotoreceptors major organelles and is responsible for all cell functions other than photoreceptor. ; also releases neurotransmitters
inner segment of rods and cones cell structure `mitochondria, golgi apparatus, nuclei, rods/cones
in cones discs are infoldings of the plasma membrane, outer segment tapers to blunt point
in rods discs areeach independent entity, outer segment forms an elongated cylinder
outer segment of rods and cones containsflattened membranous plates (discs) that contain visual pigments
outer segment of rods and cones cell structure discs and connecting stalks
pigment epithelium absorbs photons that are not absorbed by visual pigments
pigment epithelium does what to old discsphagocytizes old discs shed from the tip of the outer segment

Section 4

Question Answer
rhodospin molecules containretinal and ospin
color visionintegration of information from red, green and blue cones
color blindnessinability to detect certain colors; cones might be missing or present but unable to produce visual pigments to absorb light of that frequency
nyctalopianight blindness; can result from deficiency of vitamin A
photoreceptionphoton strikes retinal portion of photopigment molecule embedded in membrane of disc
what alters the frequency of action potetntials produced in the photo receptorthe light energy of the photon
visual pathwaysbegin at photoreceptors; end at visual cortex of cerebral hemispheres
visual pathways synapsetwice before it head toward brain; at the photoreceptor to the bipolar cell and the bipolar cell to the ganglion cell
central processing of visual information 1axons from ganglion cells converge on optic disc
central processing of visual information 2penetrate wall of eye, proceed toward diencephalon as optic nerve II
central processing of visual information 3two optic nerves reach diencephalon at optic chasm
central processing of visual information 4half the fivers travel to the contralateral lateral geniculate nucleus, half to the ipsilateral side

Section 5

Question Answer
visual data processed byoptic radiation
optic radiationbundle of projection fibers linking lateral geniculate with visual cortex
from combined field of vision optic radiationarrive at visual cortex of opposite occipital lobe
depth perceptionobtained by comparing relative positions of objects between left eye and right eye images
circadian rhythmsome fibers from lateral geniculate nucleus goes to hypothalamus (affects day night cycle and other metabolic processes