structures of the eye Flashcards
lacrimal apparatus
protects, moistens, and lubricates the eye
lacrimal gland
produces lacrimal fluid (tears)
lacrimal canals
drains lacrimal fluid from the eyes
lacrimal sac
provides passage of lacrimal fluids to nasal cavity
nasolacrimal duct
empties lacrimal fluid into the nasal cavity
sclera
thick white connective tissue, “white of the eyes”
cornea
transparent, central anterior portion, allows for light to enter the eye
choroid
a dark pigment in the middle of the eye that prevents light from scattering w/i the eye
ciliary body
a smooth muscle structure w/i the choroid to which the lens and iris are attached
suspensory ligament
fibers that connect the ciliary body with the lens
lens
transparent biconvex structure, divides the eye into anterior and posterior chamber, focuses light rays onto the retina
iris
pigmented layer that gives eye color
pupil
rounded opening in the iris that controls the amount of light directed to the retina, dilates and constricts to control light
retina
innermost sensory tunic of the eye (light-sensitive nerve tissue) containing photoreceptors; converts light into electrical impulses
photoreceptors (rods & cones)
rods: edge of retina, allow dim light and peripheral vision
cones: center of retina, allow for detailed colored vision
optic nerve
composed of ganglion cell axons, transmits electrical impulses from the eyes to the brain
optic disk (blind spot)
no photoreceptors at the OD, results in break in the visual field
macula
translates light that enters the eye into the images we see; responsible for center vision that lets you see what’s right in front of you
fovea centralis
a small pit in the macula provides sharp central vision (reading, driving, sowing)
cataracts
the hardening of the lens resulting in hazy vision and eventually blindness
glaucoma
optic condition caused by a blocked aqueous humor, compression of the retina and optic nerve; causes pain and possible blindness
aqueous humor
watery fluid found in the anterior chamber, helps maintain intraocular pressure, provides nutrients for the lens and cornea
vitreous humor
clear gel-like substance in the posterior chamber, provides reinforcements that keep the eye from collapsing; refractory structure
scleral venous sinus (canal of schlemm)
at the junction of the sclera and cornea, collects aqueous humor and delivers it to the bloodstream
accommodation
the ability of the eye to focus on objects less than 20ft away
optic chiasma
conveys visual info from the eye to the occipital lobe
optic tracts
bundle of nerve fibers carrying visual info from the optic chiasma to the brain
optic radiation
axons in the thalamus, transmits visual input from the retina, optic nerve, and optic tract
convergence
the reflexive movement of the eyes medially when viewing close objects
photopupillary reflex
eyes constricting when exposed to bright light
accommodation pupillary reflex
pupils constricting when viewing close objects to provide more acute vision
emmetropia
normal eye vision
hypermetropia or hyperopia
being farsighted; light rays are focused behind retina
myopia
being nearsighted; light focused in front of retina
presbyopia
near and far is blurry; caused by weak ciliary muscles or decreased convexity of lens
astigmatism
unusual curvature of cornea
