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a&p vocab Vision


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lacrimal apparatus consists of the
lacrimal glad, lacrimal canaliculi, lacrimal sac, and the nasolacrimal duct
lacrimal glands
superior to the lateral aspect of each eye. continually dilute tears that flow onto the anterior surface of the eyeball through several small ducts
lacrimal puncta
tiny openings of the lacrimal canaliculi through which earsflush across the eyeball
nasolacrimal duct
empties into the nasal cvity
antibaterial secretion contained in the lacrimal secretion`
medial and lateral commissures
the junctions of the upper and lower eyelids
lacrimal caruncle
fleashy elevation at the medial commisure that produces a whitish oily secretion
a mucous membran that lines the internal surface of the eyelids (palpebral conjunctiva) and continues over the anterior surface of the eyeball to its junction with the corneal epithelium (bulbar conjunctiva) secretes mucus to lubricate the eyeball
inflammation of the conjunctiva
ciliary glands
modified sweat glands that lie between the eyelash hair follicles and help lube the eyeball
tarsal glands
located posterior to the eyelashes, secretes and oily substance
an inflammation of one of the ciliary glands or a small oil gland
extrinsic eye muscles
6 of them attach to the exerior surace of each eyeball to control eye movements and make it possible for the eye to follow a moving object.
Lateral Rectus
Extrinsic eye muscle that moves the eye lateraly
medial rectus
extrinsic eye muscle that moves the eye medially
superior rectus
ex. eye muscle... elevates eys and turns it eye medially
inferior rectus
ex. eye muscle- deperesses eye and turns it medially
inferior oblique
ex. eye muscle elevates eye and turns it laterally
superior oblique
ex eye muscle that depresses the eye and turns it laterally
3 layers of the eye
Fibrous- outer layer Uvea- middle layer Sensory layer- inner layer
fibrous layer
outer layer of eye- protective layer- dense avascular CT- 2 regions SCLERA and CORNEA
region of the fibrous layer- opaque white forms bulk of fibrous layer
part of the fibrous layer- anterior most portion- where light enters the eye
the middle layer of the eye- vascular layer- 4 parts: choroid, ciliary body, iris, pupil
posteriormost part of the uvea- blood rich nutritive region contains dark pigment that prevents light scattering w/in the eye
ciliary body
anterior part of the uvea- chiefly composed of ciliary muscles which are imp. in controlling the lens shape, and ciliary processes (which secrete aqueous humor)
most anterior part of the uvea- contains the pigment- in close vision and bright light the pupil is little and vise versa
hole in the iris that lets light pass
sensory layer (retina)
innermost layer of the eye- 2 layers: outer pigmented epithelium and inner neural layer
pigmented epithelium
outer layer of the retina- extends anteriorly to tcover the ciliary body and posterior side of the iris
Neural layer
transparent inner layer of the retina which extends anteriorly onluy to the ciliary body- contains rods and cones
Rods and cones
photoreceptors contained in the neural layer of the retina
optic disc
\"blind spot\" the place where there are no photoreceptor cells- where the optic nerve leaves the eyeball
macula lutea
yellow spot- area of high cone density- lateral to each blind spot and posterior to the lens
fovea centralis
center of the macula lutea- a minute pit which contains mostly cones and is the area of greatest visual acuity- focusing for discriminitive vision
a flexible crystalline structure- focuses light on the retina- divides eye into 2 segments: anterior segment and posterior segment
supensory ligament (ciliary zonule)
attached to the ciliary body- holds lens in place
where the lens becomes increasingly hard and opaque
anterior segment
anterior the lens contains acqueous humor- divided into anterior and posterior chambers
acqueous humor
a thin, watery substance contained in the anterior segment- helps to maintain the intraocular pressure of the eye and provides nutrients for the avascular lens and cornea
posterior segment
behind the lens- filled w/ vitreous humor
vitreous humor
gel like substance that fills the posterior segment- provides the major internal reinforcement of the posterior part of the eyeball, and helps to keep the retin pressed firmly against the wall- formed only before birth
ciliary processes
continually forms acqueous humor
Inner nervous layer of the retina composed of 3 major neuronal compositions____
photoreceptors, bipolar cells, gnglion cells
specialized receptors for dim light- most numberous in the periphery
color receptors that permit hight levels of acuity but fnction only under conditions of high light intensity; most found in fovea centralis-
optic nerve
tight bundle of finbers leaving the retina
optic chiasma
where the fibers from the medial side of each eye cross over to the opposite side.
optic chasma
where the fibers from the medial side of each eye cross over to the opposite side
optic tracts
the fiber tracts formed by the optic chiasma- each optic tract contains fibers romt he lateral side of the eye on the same side and from the medial side of the opposite eye
lateral geniculate body
where the optic tract fibers synapse with neurons- part of the thalamus
optic radiation
formed by the axons of the geniculate body
visual cortex
in the occipital lobe of the brain- where the axons of the lateral geniculate body/ optic radiation synapse with thte cortical cells, and visual interpretation occurs
when light rays are bent. Light rays in the visual field are refracted as they encounter the cornea, lens, and viteous humor of the eye
the ability of the eye to focus diferentially for objects of near vision (less than 5 m, or 20 ft)
real image
the image formed on the retina as a result of the refractory activity of the lens (reversed from left to reight, inverted, and smaller than the object
emmetropic eye
normal eye- able to accomodate properly
problems resulting from from an eye not being able to accomodate properly:
1) from lenses that are too strong or too lazy (overconvergin and underconverging, respectively 2) from structural problem such as an eyebll that is too long or too short to provide for proper focusing by the lens 3) from a cornea or lens with improper curvatures
nearsightedness- can see close objects w.out difficulty ut distant objects are blurred or seen indistinctly- correction requires a concave lens
where the image focuses behind the retina- farsightedness- can\'t see close up- need convex lenses to augment the convergin power of the lens for close vision
caused by irregularities in the curvatures of the lens and/or cornea lead to blurred vision- need cylindrically ground lenses- compensate for inequalities in the curvatures of refracting surfaces
old vision- elasticity of lens decreases w/ age- difficulty near or close vision
near point of accommodation
tests the elasticity of lenses
visual acuity
sharpness of vision- tested w/ Snellen eye chart
binary vision
2 eyed- both eyes look in approximately same direction- see slightly diff views- their visual fields overlap to a considerable extent- provides 3-D vision and accurate means of locating objects in space
eyes are more on the side of the head- see in 2 diff directions
medial eye movements- essential for near vision- produced by the extrinsic muscles

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