Chp 11 Sensory Organs MedTerms Definitions

angle where the eyes meet

hair cells

provides stiffness of the eye giving shape

provides protective layering

• sclera: white part of the eye; maintains shape, tough fibrous tissue
• chroid: middle layer that contains many blood vessels
• retina: sensitive and innermost layer; receives nerve impulses and transmits them to the brain

• anterior chamber: behind the cornea, in front of the iris
• posterior chamber: behind the iris, in front of ligaments

ANTERIOR SEGMENT MAKES UP 1/3 OF THE EYE FILLING IT WITH AQUEOUS HUMOR

makes up 2/3 of the eyeball filling it with vitreous humor that contains millions of fibers.

• rods: black and white
• cones: color

light sensitive area in the center of the retina

middle pit of macula and contains ONLY CONES, no rods since it has high concentrations of color

"blind spot" NO CONES AND RODS

pigmented layer of the eye

located in chroid layer, set of muscles that adjust thickness of lens to focus.

colorful circular structure that surrounds the pupil; controls amount of light passing through by contracting muscles

focuses light rays entering the eye

black circular opening which permits light to enter the eye

process whereby the eyes make adjustments for seeing objects at various distances

inward movement of the eyes towards each other

normal relationshpi between the refractive POWER for the eye and the SHAPE of the eye that enables light rays to focus correctly on the retina

ability of the lens to bend light rays so they focus on the retina

ability to distinguish object details and shape at distance

drooping of the upper eye lid due to paralysis

nodule or cyst usually on the upper eye lid

eversion of the eyelid; turning it outwards

inversion edge of the eyelid; inward eyelid

"stye" pus filled and painful lesion on the eye

swelling of the tissues surrounding the eye(s)

bleeding between the conjunctiva and the sclera

inflammation of the uvea

scratch to cornea

damage to retina due to complication of DM

condition where the pupils are unequal in size

loss of transparency of the lens that causes a progressive loss of visual clarity

particles of cellular debris that float in the vitreous humor casting shadows

presence of what appears to be flashes of light

contraction of pupil in response to light, prescription of illegal drugs

dilation of the pupil caused by injury, disease or drugs

involuntary, constant movement of the eyeball.

swelling and inflammation of the optic nerve at point of entrance through optical disc

progressive degeneration of the retina that affects night and peripheral vision.

group of diseases characterized by increased intraocular pressure that damages the retinal nerve fibers and optic nerve. BLOCKAGE OF FLOW OUT OF THE EYE.

trabecular mesh is gradually blocked causing pressure

fluid cannot reach trabecular mesh causing pressure in the front of the eye

progressive condition where macula is damaged, resulting in loss of vision; not blind.

double vision

blindness in one half of the visual field

color blindness

night blindness

excessive sensitivity to light causing headache

change in vision relating to aging

disorder in which the eyes point in a different direction or are not aligned correctly

cross eyed

snake eyes

focusing problem that occurs when lens and cornea do not bend light

images do not focus properly on the retina

uneven curvatures of the cornea causing inability to focus

farsighted

nearsighted

dimness of vision; partial loss

"blind spot" abnormal diminished vision surrounded by an area of normal vision.

chart measures visual acuity

unit of measurement of the lens' refractive power

Pupils are Equal, Round, Responsive, to Light and Accomodation

removal of the eyeball

inward; for myopia, nearsighted

for hyperopsia; farsighted

used to reattach the detached area in a retinal detachment

• pinna (auricle): external portion of the ear
• external auditory canal: transmits sound waves to tympanic membrane
• cerumen: earwax

• tympanic membrane: eardrum
• mastoid process: temporal bone containing hollow air space that surrounds the middle ear.

• malleus; hammer
• incus; anvil
• stapes; stirrup

auditory tube; equalizes air pressure

• LABYRINTH
• oval window; vibrations enter through here
• cochlea; sound vibrations are converted into impulses
• organ of Corti; receives vibrations and relays them to auditory nerve fibers.
• semicircular canals
• acoustic nerves

sound waves enter the ear through the pinna and travel down the external auditory canal then strike the eardrum

eardrum vibrates and causes the auditory ossicles of middle ear to vibrate.

sound vibrations reach the inner ear.

pressure related condition caused by change in altitude; flying in an airplane, driving in the mountains.

epidermal cyst in the middle composed of epithelial cells and cholesterol

ankylosis of the bones of the middle ear; conductive hearing loss

rare chronic disorder in which the amount of fluid in the inner ear increases intermittently.

ringing, buzzing in the ear.

gradual loss of sensorineural hearing

occurs when sound waves are prevented from passing from the air to the fluid filled inner ear; earwax buildup, infection,

damage to hair cells within the ear. "nerve deafness"

use of a tuning fork to distinguish between conductive and sensorineural hearling losses

surgical procedure in which a new opening is created in the labyrinth to restore hearing loss