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

Transcription

1 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

2 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. Ciliary Body Conjunctiva Iris Pupil Anterior Chamber Cornea Lens Retina Blood Vessels Path of Light Optic Nerve Vitreous Humor Choroid Sclera Choroid 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. Revised

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

4 eso- exo- extra- intra- inward outward on the outside on the inside Term Analysis and Definition (The Eye) Word Part Term Term Analysis Definition aque/o aqueous humor aque = water -ous = pertaining to humor = body fluid Pertaining to the watery fluid found in the anterior chamber of the eye. blephar/o, palpebr/o blepharoptosis blephar = eyelid -ptosis = drooping Drooping of the eyelid palpebral palpebr = eyelid -al = pertaining to Pertaining to the eyelid chori/o, choroid/o chorioretinitis chori = choroid -itis = inflammation retin = retina Inflammation of the choroid and retina choroiditis Inflammation of the choroid conjunctiv/o conjunctivitis conjunctiv = conjunctiva -itis = inflammation Inflammation of the conjunctivia (Also known as pinkeye ) core/o pupill/o coreometer core = pupil -meter = instrument to measure Instrument used to measure the size of the pupil pupillary pupil l= pupil -ary = pertaining to Pertaining to the pupil corne/o, kerat/o corneal corne = cornea -al = pertaining to Pertaining to the cornea keratoconus kerat = cornea -conus = cone shaped Abnormal, cone-shaped protrusion of the cornea cycl/o cycloplegia cycl = ciliary body -plegia = paralysis Paralysis of the ciliary body dacry/o lacrim/o dacryostenosis nasolacrimal dacry = tear duct -stenosis = narrowing Narrowing of the tear duct Revised

5 Word Part Term Term Analysis Definition nas = nose lacrim = tear -al = pertaining to Pertaining to the nose and tear (lacrimal) apparatus irid/o, ir/o iritis irid = iris -itis = inflammation Inflammation of the iris iridectomy -ectomy = excision Excision of the iris mi/o miosis mi = contraction, less, smaller -osis = abnormal condition Abnormal contraction of the pupil miotic -tic = pertaining to 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 bi = two ocul = eye -ar = pertaining to extra = outside -ar = pertaining to Pertaining to both eyes Pertaining to the outside of the eye intraocular intra = inside, within Pertaining to within the eye exophthalmia ex = outward ophthalm = eye -ia = condition Condition where there is outward protrusion of the eyeball ophthalmologist -logist = specialist Specialist in the study and diagnosis of diseases of the eye ophthalmology -logy = study of Study of diseases of the eye opt/o optic opt = vision, sight -ic = pertaining to Pertaining to vision or sight optician -ician = specialist, expert One who specializes in prescribing glasses for improving sight optometrist Revised

6 Word Part Term Term Analysis Definition -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 disc edema = accumulation of fluid Accumulation of fluid in the optic disc phac/o, phak/o aphakia phacomalacia a = no, lack of phak = lens ia = condition phac = lens -malacia = softening Absence of a lens Softening of a lens phot/o photophobia phot = light -phobia = fear retin/o retinopathy retin = retina -pathy = disease scler/o sclerectomy scler = sclera -ectomy = excision, surgical removal ton/o tonometry ton = tension -metry = process of measuring uve/o uveitis uve = uvea -itis = inflammation vitre/o vitreous humor vitre = gel-like -ous = pertaining to Fear of or intolerance to light Disease of the retina Surgical excision of the sclera Measurement of the intraocular pressure Inflammation of the uvea of the eye Pertaining to the gel-like substance in the posterior cavity of the eye -chalasis blepharochalasi s blephar = eyelid -chalasis = relaxation Relaxation of the eyelid -tropia esotropia eso = inward -tropia = turning Turning inward of the eyeball. Also referred to as cross-eyes exotropia exo = outward Turning outward of the eyeball -opia, -opsia amblyopia ambly = dull, dim -opia = vision Dimness of vision Revised

7 Word Part Term Term Analysis Definition diplopia di = double Double vision presbyopia presby = old age Impaired vision due to aging hyperopia hyper = above, excessive Farsightedness ( the light rays go beyond the retina) myopia my = to shut (Light rays focus in front of the retina) nearsightedness -tropion ectropion ec = out -tropion = turning Outward turning of the eyelid entropion en = inward Inward turning of the eyelid Vocabulary Words: Accommodation Cararact Conjunctivitis Enucleation Glaucoma Nystagmus Snellen Chart Strabismus The process whereby the eyes make adjustments for seeing objects at various distances An opacity of the crystalline lens or its capsule; most often occurs in adults past middle age. Inflammation of the conjunctiva caused by allergy, trauma, chemical injury, bacterial, viral or infection. The type pinkeye is infectious and contagious A process of removal of the eyeball from the orbit A disease characterized by a increased intraocular pressure which results in atrophy of the optic nerve and blindness An involuntary, constant, rhythmic movement of the eyeball A chart for testing visual acuity a squint Abbreviations: OP OD OS intraocular pressure oculus dexter (right eye) oculus sinister (left eye) Revised

8 PERLA REM pupil equal and reactive to light and accommodation 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. Malleus Incus Auricle Semicircular Canals External ear Canal Cochlea Eustachian tube Tympanic Membrane Stapes External Ear Composed of the auricle, external auditory meatus, and eardrum or the tympanic membrane. 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 Revised

9 Middle Ear auditory canal. It is responsible to channel the sound waves toward the eardrum. 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 audi/o, audit/o aur/o, aur/i,ot/o cochle/o labyrinth/o mastoid/o myring/o, tympan/o myc/o hearing, related to hearing hearing, ear ear, hearing cochlea (snail, spiral) labyrinth, inner ear mastoid process ear drum, tympanic membrane fungus Revised

10 pinn/i salping/o staped/o tinnit/o external ear eustachian tube stapes ringing, buzzing Suffixes -algia, -dynia -cusis pain hearing Prefixes bi- mon- two one Term Analysis and Definition (The Ear) Word Part Term Term Analysis Definition audio/o, audit/o audiogram audio = hearing -gram = record Record of hearing audiometry -merty = process of measuring Measurement of hearing auditory audit = hearing -ory = pertaining to Pertaining to hearing aur/o, ot/o, aur/i aural aur = ear -al = pertaining to Pertaining to the ear otalgia ot = ear -algia = pain Earache otitis media -itis = inflammation media = middle Inflammation in the middle ear otorrhea -rrhea = discharge Discharge from the ear otoscope -scope = instrument to visually examine Instrument to visually examine the ear otosclerosis -sclerosis = hardening Hardening of the bones of the ear otorrhagia -rrhagia = bleeding Bleeding from the ear Revised

11 Word Part Term Term Analysis Definition cochle/o cochlear cochle - cochlea -ar = pertaining to labryinth/o labyrinthitis labyrinth = inner ear -itis = inflammation mastoid/o mastoidectomy mastoid = mastoid bone -ectomy = surgical removal Pertaining to the cochlea Inflammation of the inner ear Surgical removal of the mastoid bone myring/o, tympan/o myringotomy myring = ear drum -tomy = surgical incision Surgical incision into the ear drum tympanocentesis -centesis = puncture to remove fluid 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 Equilibrium Vertigo earwax a state of balance a feeling of dizziness Abbreviations: AD auris dexter (right ear) Revised

12 AS auris sinistra (left ear) ENT ear, nose and throat EENT eyes, ears, nose throat Revised