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18 terms

The Visual System - Organization

Terms and their definitions about certain parts of the human eye (p.33 of physiology notes)
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sclera
white outerlayer of connective tissue (eyewhite);
function = protection
cornea
transparent extension of sclera;
function = provides focusing (along with lens), high reflection of light rays inside
choroid
thin pigmented inner layer;
covers entire eyeball, contains blood vessels and pigmented tissue (melanin)
iris
circular and radial fibers with opening in the center (pupil);
nerve III
lens
focusing system; its curvature is controlled by ciliary smooth muscle
superior rectus muscle
the fastest muscle in the body, therefore making the eye the fastest moving organ; nerve III, IV
anterior chamber (anterior cavity)
space between iris and cornea filled with aqueous humor
vitreous body (posterior cavity)
non-circulating, non-absorbing, permanent gelatinous, clear substance
details vitreous body (posterior cavity)
sciliary process in here = secrete aqueous humor --> goes to anterior chamber and exists through the canal of schlemm (completes circulation in 2-3 hours)
retina
layers of specialized nerve cells responsible for image formation; first image formed here; blood supply here
fovea
center of the retinal visual field containing cones only (also called the macula) = seeing color
optic disc
exit point of optic nerve fibers (axons of the ganglion neurons); blind spot with no photoreceptors; entry of retinal arteries and veins
optic nerve (cranial nerve II)
consists of 1 million optic nerve fibers that travel to the brain
accommodation
adjusting of pupil to focus on objects at different distances
circular accommodation
constriction = making pupil smaller
radial accommodation
contraction = dilation of pupil; can increase/decrease by 16-fold
glaucoma
disease of anterior chamber with pressure build up due to problems with secretion, flow, and/or absorption
cataract
cloudiness in lens