ch. 14

receptors

sensory nerve endings that respond to various kinds of stimulation.

special sense organs

the eyes

pupil

light rays enter here
the small dark circular structure in the center of the eye

iris

surrounds the pupil
the colored portion of the eye that we regularly see

function: contracts or relaxes to control the amount of light entering the eye through the pupil

sclera

The tough outer layer of the eye

the white opaque membrane covering most of the eyeball.

function: external protection

conjunctiva

the mucous membrane lining the inner surface of the eyelid that acts as a protective covering for the exposed surface of the eye.

lacrimal glands

produce and store tears (lacrimal fluid)

small lacrimal ducts

Tears pass through these openings into here

large nasolacrimal sac

from small lacrimal ducts

tearing

If more lacrimal fluid is produced than can be removed

cornea

the transparent structure at the front of the eyeball that bends or refracts light rays so they are focused properly on the sensitive receptor cells in the posterior region of the eye.

function: refraction of light

choroid

a dark brown membrane inside the sclera that is continuous with the iris and the ciliary body on the anterior surface of the eye.

function: blood supply

lens

The ciliary body surrounds the outside of the this in a circular fashion

refraction

changes in the lens cause ___________ of light rays on the posterior region of the eye

accommodation

refractory adjustment for close vision

anterior chamber

The ciliary body also secretes a fluid called aqueous humor

vitreous chamber

cavity of the eye
filled with a soft

vitreous humor

soft

retina

the delicate nervous tissue membrane of the eye

optic disc

the region of the eye where the optic nerve meets the retina. There are no light receptors in the optic disc

therefore

it is known as the blind spot of the eye.

ciliary body

function: secretion of vitreous fluid

external ocular muscles

function: movement of eyeball

eyelid

function: protection of the eye

optic nerve

function: transmission of visual information tot he brain

rods and cones

sensitive receptor cells of the retina

rods

distinguish light from dark

cones

color vision

choroid/o

choroid

chrom/o

color

conjunctiv/o

conjunctiva

corne/o

kerat/o

dacry/o

lacrim/o

ir/o

irid/o

ocul/o

ophthalm/o

opt/o

optic/o

presby/o

old or old age

pupill/o

pupil

retin/o

retina

ton/o

tone or tension

Snellen chart

used to measure visual acuity/clearness or sharpness of vision

ophthalmometer

an instrument used to measure the eye

myopia

is nearsightedness

parallel rays entering the eye are focused in front of the retina.

hyperopia

is farsightedness

rays of light entering the eye are brought to focus behind the retina.

astigmatism

is uneven focusing of the image

tonometry

measurement of the intraocular pressure using a tonometer usually after numbing the eye with an anesthetic.

assessment of visual fields

determines the physical space visible to an individual in a fixed position

mydriatic

agent that dilates the pupil

presbyopia

is hyperopia and impairment of vision due to advancing years or old age.

accommodation reflex

the ability of the eye to adjust to variations in distance.

fluorescein angiography

procedure uses fluorescein (a bright green fluorescent dye) to examine movement of blood through blood vessels in the eye.

amblyopia

strabismus

blepharitis

inflammation of the eyelid

cataract

An abnormal progressive condition of the lens

color vision deficiencies

achromatic vision
achromatopsia
daltonism

achromatopsia

profound inability to see color

conjunctivitis

inflammation of the conjunctiva
aka: red eyes or pink eye

glaucoma

An abnormal condition of increased pressure within the eye. Prolonged pressure can damage the retina and optic nerve.

hordeolum

Sty or stye

macular degeneration

A progressive deterioration of the retina associated with new vessel formation that can progress to blindness

nyctalopia

Poor vision at night or in dim light

photophobia

Excessive sensitivity of the eyes to light

ptosis

drooping of the upper eyelids

retinal detachment

Separation of the retina from the choroid

retinopathy

Any disease of the retina.

Diabetic retinopathy is an abnormality of the retina caused by diabetes mellitus

iridectomy

surgical removal of part of the iris

it is performed to restore proper drainage for patients with glaucoma

cerumen

Several glands secrete this yellowish

tympanic membrane

eardrum

cochlea

a spiral tunnel

oval window

separates the middle ear from the inner ear

semicircular canals

fluid-filled canals that open into the cochlea.

auditory or eustachian tube

leads from the middle ear to the pharynx (throat). This tube can prevent damage to the eardrum by equalizing pressure in the middle ear to the atmospheric pressure.

-ory

pertaining to

acoust/o

audi/o

adenoid/o

adenoids

aur/o

auricul/o

cerumin/o

ear wax

cochle/o

cochlea

myring/o

tympan/o

salping/o

eustachian tube

otoscopic examination

otoscopy

audiologist

detects and evaluates hearing loss and determines how a patient can best make use of remaining hearing.

audiometer

an electronic device for measuring hearing.

The record produced is an *audiogram*

tuning fork tests

screen for both function of the auditory nerve and ability of ear structures to conduct sound waves to the inner ear

otitis

inflammation of the ear

otorrhea

discharge from the ear that may contain blood

otalgia

pain in the ear
earache

otitis media

inflammation of the middle ear

myringitis

inflammation of the tympanic membrane

mastoiditis

an infection of one of the mastoid bones of the skull

otitis externa

otomycosis

otitis interna

is inner ear infection

otosclerosis

hardening of the ear.

This condition is caused by formation of spongy bone around structures of the middle and inner ear.

It is hereditary and leads to hearing impairment.

tinnitus

noise in the ears

vertigo

dizziness

cochlear implant

in complete hearing loss

otoplasty

surgical repair or reconstruction of the external ear.