chapter 9 - healthtraining.cahealthtraining.ca/images/documents/chapter 8 sept 2003.doc · web...

Chapter 8 The Sensory System

Chapter Objectives

Upon completion of the chapter the participant will be able to:

1. Describe the structures involved with hearing.2. Describe the structures involved with seeing.3. Discuss the physiology of being able to see.4. Discuss the physiology of being able to hear.5. Analyze, define, spell and pronounce the medical terms common to the ear.6. Analyze, define, spell and pronounce the medical terms common to the eye.7. Successfully complete the review exercises at the end of the chapter.

The Eye

Our eyes are the receptor organs for the sense of sight and provide the window that lets in the light of the outside world. Light waves are transformed by the eye into nerve impulses that are sent to the occipital lobe of the brain. Here the waves are processed and we experience vision.

It is the job of the eye to let light in, focus it, transform it into an impulse and send the impulse to the brain. Light enters the eye through the pupil (pupil/o, core/o) and then passes through the lens (phac/o, phak/o) found behind the pupil. The lens has the ability to adjust its shape in order to adjust to objects that are close at hand and those that are at a distance. As many people age their lens may become cloudy which will affect their ability to see. This condition is referred to as cataracts. The light from the lens then goes to the back of the eyeball where it strikes the retina (retin/o). It is the retina that transforms the image into a nerve impulse. The impulses travel along the optic nerve to the brain.

The eye consists of two parts: the inner eye and the outer eye.

Inner Eye

Consists of three layers: outer, middle and inner Outer layer consists of the cornea (corne/o, kerat/o) and the sclera (scler/o).

The cornea is the transparent anterior portion of the sclera that allows light into the eye and allows for focusing of the light on the back of the eye. The sclera is known as the “white of the eye” which maintains the shape of the eye and protects the delicate inner structures.

Middle layer is the vascular layer and is referred to as the uvea (uve/o) and consists of the choroid (choroid/o) the ciliary body (cycl/o) and iris (ir/o, irido/, irit/o, ir/i). The choroid is the inner lining of the sclera and has the blood vessels that nourish the eye. The ciliary body consists of muscles that change the shape of the lens so you are able to see things at various distances. This process is

Revised August 2003 -83-

referred to as accommodation. The ciliary body is responsible to produce a liquid that bathes the anterior surface of the eye.

The iris is the circular colored part of the eye. The center of the iris is a circular opening called the pupil (pupill/o, core/o) that regulates the amount of light that can get into the eye. In bright light the pupil will constrict and in darkness it will dilates.

Inner layer consists of the retina. This is nerve tissue made up of rods and cones. They transform light into nerve impulses.

Outer Eye

The outer eye consists of the orbital cavity, ocular muscles, the eyelids (palpebr/o, blephar/o) the conjunctival membrane (conjunctiv/o) and the lacrimal apparatus (lacrim/o, dacry/o). The orbital cavity acts as a protective device for the eyeball. The six muscles allow the eye to move in all directions. The eyelid acts as a protection from dust and dirt entering the eye and the membrane lubricates as well as protects the eyeball. The lacrimal glands produce tears that continuously bathe the eye. The tears drain into the back of the nasal cavity that explains why your nose runs when you cry.


Ciliary Body

Conjunctiva

Cornea

Anterior ChamberPath of Light

Blood Vessels

Optic Nerve

Vitreous

Sclera

Choroid

Iris

Pupil

Lens

Choroid

Retina

Word Parts for the Eye

aque/o water blephar/o, palpebr/o eyelid chrom/o color chori/o, choroid/o choroids conjunctiv/o conjunctiva core/o, pupill/o pupil corne/o, kerat/o cornea cycl/o ciliary body dacry/o, lacrim/o tear/lacrimal duct, tears dipl/o double irid/o, ir/o, ir/i, irit/o iris mi/o contraction, less, smaller mydri/o wide, dilation ocul/o, ophthalm/o, opt/o, optic/o, opt/i eye, vision, sight papill/o optic disc phac/o, phak/o lens phot/o light presby/o old age retin/o retina scler/o sclera ton/o tension uve/o uvea vitre/o glasslike, glassy, gel like -chalasis relaxation -opia, -opsia vision, visual condition -ptosis drooping, sagging -pexy put in place -tropia, -tropion turning


Iris

ScleraPupil

Lacrimal Gland

Conjunctiv

Nasolacrimal

eso- inward exo- outward extra- on the outside intra- on the inside

Term Analysis and Definition (The Eye)

Word Part Term Term Analysis Definition

aque/o aqueous humor

aque = water-ous = pertaining tohumor = body fluid

Pertaining to the watery fluid found in the anterior chamber of the eye.

blephar/o, palpebr/o

blepharoptosis

palpebral

blephar = eyelid-ptosis = drooping

palpebr = eyelid-al = pertaining to

Drooping of the eyelid

Pertaining to the eyelid

chori/o, choroid/o

chorioretinitis

choroiditis

chori = choroid-itis = inflammationretin = retina

Inflammation of the choroid and retina

Inflammation of the choroid

conjunctiv/o conjunctivitis conjunctiv = conjunctiva-itis = inflammation

Inflammation of the conjunctivia(Also known as “pinkeye”)

core/o pupill/o

coreometer

pupillary

core = pupil-meter = instrument to measure

pupil l= pupil-ary = pertaining to

Instrument used to measure the size of the pupil

Pertaining to the pupil

corne/o, kerat/o

corneal

keratoconus

corne = cornea-al = pertaining to

kerat = cornea-conus = cone shaped

Pertaining to the cornea

Abnormal, cone-shaped protrusion of the cornea

cycl/o cycloplegia cycl = ciliary body-plegia = paralysis

Paralysis of the ciliary body

dacry/olacrim/o

dacryostenosis dacry = tear duct-stenosis =

Narrowing of the tear duct


Word Part Term Term Analysis Definitionnasolacrimal narrowing

nas = noselacrim = tear-al = pertaining to

Pertaining to the nose and tear (lacrimal) apparatus

irid/o, ir/o iritis

iridectomy

irid = iris-itis = inflammation

-ectomy = excision

Inflammation of the iris

Excision of the iris

mi/o miosis

miotic

mi = contraction, less, smaller-osis = abnormal condition

-tic = pertaining to

Abnormal contraction of the pupil

Pertaining to a drug that constricts the pupil

mydri/o mydriatic mydri = wide, dilation-tic = pertaining to

Pertaining to a drug that dilates the pupil

ocul/o, opt/o, optic/o, opt/i, ophthalm/

binocular

extraocular

intraocular

exophthalmia

ophthalmologist

ophthalmology

bi = twoocul = eye-ar = pertaining to

extra = outside-ar = pertaining to

intra = inside, within

ex = outwardophthalm = eye-ia = condition

-logist = specialist

-logy = study of

Pertaining to both eyes

Pertaining to the outside of the eye

Pertaining to within the eye

Condition where there is outward protrusion of the eyeball

Specialist in the study and diagnosis of diseases of the eye

Study of diseases of the eye

opt/o optic

optician

opt = vision, sight-ic = pertaining to

-ician = specialist, expert

Pertaining to vision or sight

One who specializes in prescribing glasses for improving sight



optometrist-metrist = specialist in the measurement of

Specialist in the testing of visual function and in diagnosis and nonsurgical treatment of eye conditions.

papill/o papilledema papill = optic discedema = accumul-ation of fluid

Accumulation of fluid in the optic disc

phac/o, phak/o

aphakia

phacomalacia

a = no, lack ofphak = lensia = condition

phac = lens-malacia = softening

Absence of a lens

Softening of a lens

phot/o photophobia phot = light-phobia = fear

Fear of or intolerance to light

retin/o retinopathy retin = retina-pathy = disease

Disease of the retina

scler/o sclerectomy scler = sclera-ectomy = excision, surgical removal

Surgical excision of the sclera

ton/o tonometry ton = tension-metry = process of measuring

Measurement of the intraocular pressure

uve/o uveitis uve = uvea-itis = inflammation

Inflammation of the uvea of the eye

vitre/o vitreous humor vitre = gel-like-ous = pertaining to

Pertaining to the gel-like substance in the posterior cavity of the eye

-chalasis blepharochalasis

blephar = eyelid-chalasis = relaxation

Relaxation of the eyelid

-tropia esotropia

exotropia

eso = inward-tropia = turning

exo = outward

Turning inward of the eyeball. Also referred to as “cross-eyes”

Turning outward of the eyeball



-opia, -opsia

amblyopia

diplopia

presbyopia

hyperopia

myopia

ambly = dull, dim-opia = vision

di = double

presby = old age

hyper = above, excessive

my = to shut

Dimness of vision

Double vision

Impaired vision due to aging

Farsightedness ( the light rays go beyond the retina)

(Light rays focus in front of the retina) nearsightedness

-tropion ectropion

entropion

ec = out-tropion = turning

en = inward

Outward turning of the eyelid

Inward turning of the eyelid

Vocabulary Words:

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

Cararact An opacity of the crystalline lens or its capsule; most often occurs in adults past middle age.

Conjunctivitis Inflammation of the conjunctiva caused by allergy, trauma, chemical injury, bacterial, viral or infection. The type ‘pinkeye’ is infectious and contagious

Enucleation A process of removal of the eyeball from the orbit

Glaucoma A disease characterized by a increased intraocular pressure which results in atrophy of the optic nerve and blindness

Nystagmus An involuntary, constant, rhythmic movement of the eyeball

Snellen Chart A chart for testing visual acuity

Strabismus a squint

Abbreviations:

OP intraocular pressure


OD oculus dexter (right eye)

OS oculus sinister (left eye)

PERLA pupil equal and reactive to light and accommodation

REM rapid eye movement

The Ear

The ear is the sensory organ that allows us to hear. It consists of the external ear, middle ear and inner ear. The ear is responsible for hearing and as well plays an important role in our balance. The word roots audi/o, and audit/o mean hearing.

The hearing process consists of detecting and transmitting sound waves for interpretation. Detecting involves receiving the sound stimulus and then it is transmitted though a nerve called the auditory nerve to the temporal lobe of the brain where it is interpreted.

External Ear

Composed of the auricle, external auditory meatus, and eardrum or the tympanic membrane.


Cochlea

Stapes

Incus

Malleus

Auricle

SemicircularCanals

Eustachian tube

Tympanic Membrane

External ear Canal

Auricle (pinn/i, aur/o, aur/i) is also referred to as the pinna and is the external part of the ear that is attached to the head. It catches the sound waves and channels them into the external ear canal.

The canal that moves into the ear from the pinna is referred to as the external auditory canal. It is responsible to channel the sound waves toward the eardrum.

Middle Ear

The middle ear begins with the tympanic membrane (tympan/o, myring/o) or the eardrum as it is commonly referred to. When the sound waves reach the membrane they cause it to vibrate and the vibration causes the waves to travel into the middle ear.

In the middle ear are three small bones malleus, incus, and stapes. These bones are often referred to as the hammer, anvil and stirrup because of their shape. These bones begin vibrating when the sound waves hit them.

The air pressure that is found on either side of the eardrum must be kept equal. To do this there is a eustachian tube that connects the middle ear to the throat. If for some reason this tube becomes blocked a sense of pressure will build up in the middle ear and your ability to hear is affected.

The middle ear is surrounded by mastoid cells (mastoid/o) that are hollow spaces in the mastoid bone located directly behind the ear.

Inner Ear

If you think of a sponge you have a good idea of what the inner ear is like; a twisting series of canals and larger spaces. These canals and spaces are encased in bone that is referred to as the bony labyrinth (labyrinth/o).

This is the part of the ear that has the receptors needed for both hearing and your balance.

The bony labyrinth consists of the vestibule, semicircular canals and the cochlea. The vestibule and semicircular canals are important in maintaining your sense of balance. The cochlea is responsible for hearing.

Sound is transmitted into the cochlea through the oval window. In the cochlea is the organ of Corti that contains fine hair cells that move because of the sound waves. This movement stimulates the nerve cells that create the impulse that is transmitted to the brain.

Word Parts for the Ear

Roots

acoust/o, acous/o hearing, related to hearing audi/o, audit/o hearing, ear aur/o, aur/i,ot/o ear, hearing


cochle/o cochlea (snail, spiral) labyrinth/o labyrinth, inner ear mastoid/o mastoid process myring/o, tympan/o ear drum, tympanic membrane myc/o fungus pinn/i external ear salping/o eustachian tube staped/o stapes tinnit/o ringing, buzzing

Suffixes

-algia, -dynia pain -cusis hearing

Prefixes

bi- two mon- one

Term Analysis and Definition (The Ear)


audio/o, audit/o

audiogram

audiometry

auditory

audio = hearing-gram = record

-merty = process of measuring

audit = hearing-ory = pertaining to

Record of hearing

Measurement of hearing

Pertaining to hearing

aur/o , ot/o, aur/i

aural

otalgia

otitis media

otorrhea

otoscope

aur = ear-al = pertaining to

ot = ear-algia = pain

-itis = inflammationmedia = middle

-rrhea = discharge

-scope = instrument to visually examine

Pertaining to the ear

Earache

Inflammation in the middle ear

Discharge from the ear

Instrument to visually examine the ear



otosclerosis

otorrhagia

-sclerosis = hardening

-rrhagia = bleeding

Hardening of the bones of the ear

Bleeding from the ear

cochle/o cochlear cochle - cochlea-ar = pertaining to

Pertaining to the cochlea

labryinth/o labyrinthitis labyrinth = inner ear-itis = inflammation

Inflammation of the inner ear

mastoid/o mastoidectomy mastoid = mastoid bone-ectomy = surgical removal

Surgical removal of the mastoid bone

myring/o, tympan/o

myringotomy

tympanocentesis

myring = ear drum-tomy = surgical incision

-centesis = puncture to remove fluid

Surgical incision into the ear drum

Puncture in the ear drum for removal of fluid

salping/o salpingoscope salping = eustachian tube (ear)scope = instrument used to visually examine

Instrument used to visually examine the eustachian tube

staped/o,stapedi/o

stapedectomy staped = stapes-ectomy = surgical excision

Surgical excision of the stapes

tinnit/o tinnitus tinnit = ringing-us = thing

Ringing in something. Term used to refer to “ringing in the ears”

-cusis presbycusis presby = old age-cusis = hearing

Diminished hearing from old age

Vocabulary Words:

Cerumen earwax

Equilibrium a state of balance


Vertigo a feeling of dizziness

Abbreviations:

AD auris dexter (right ear)

AS auris sinistra (left ear)

ENT ear, nose and throat

EENT eyes, ears, nose throat


chapter 9 - healthtraining.cahealthtraining.ca/images/documents/chapter 8 sept 2003.doc · web...

Documents