chapter © 2011 the mcgraw-hill companies, inc. all rights reserved. 31 special senses

CHAPTER

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.

31Special Senses


31-2

Learning Outcomes

31.1 Describe the anatomy of the nose and the function of each part.

31.2 Describe how smell sensations are created and interpreted.

31.3 Describe the anatomy of the tongue and the function of each part.

31.4 Describe how taste sensations are created and interpreted.


31-3

Learning Outcomes (cont.)

31.5 Name the four primary taste sensations and the acknowledged fifth taste sensation.

31.6 Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions.

31.7 Trace the visual pathway through the eye and to the brain for interpretation.

31.8 Identify ways that patients can practice preventive eye care.


31-4


31.9 State ways that vision changes with age.

31.10 List the medical professionals involved in diagnosis and treatment of visual disorders, including the roles that each play in patient care.

31.11 List treatments for visual disorders.

31.12 Describe the causes, signs and symptoms, and treatments of various diseases and conditions of the eye.


31-5


31.13 Describe the anatomy of the ear and the function of each part.

31.14 Explain the role of the ear in maintaining equilibrium.

31.15 Explain how sounds travel through the ear and are interpreted in the brain.

31.16 State ways that hearing changes with age.


31-6


31.17 List the types of hearing loss and how they differ.

31.18 Describe treatments for ear and hearing disorders.

31.19 Explain how patients can be educated about preventive ear care.

31.20 Describe the causes, signs and symptoms, and treatments of various disorders of the ear and hearing.


31-7

Introduction

• Special senses– Sensory receptors located in head

• Nose – smell • Tongue – taste• Eyes – vision • Ears – hearing and equilibrium

– Touch is a generalized sense• Stimulus nervous system brain response


31-8

Nose and Sense of Smell

• Olfactory receptors– Chemoreceptors –

respond to changes in chemical concentrations

– Chemicals must be dissolved in mucus

– Located in the olfactory organ


31-9

Smell Sensation

that send the information along olfactory bulbs and tracts

to different areas of the cerebrum;

cerebrum interprets the information as a particular type of smell

Activation of smell receptors information sent to olfactory nerves


31-10

Nose and Sense of Smell (cont.)

• Sensory Adaptation– Chemical can stimulate receptors for

limited time

– Receptors fatigue and stop responding to chemical

– No longer smell odor


31-11

Apply Your Knowledge

ANSWER: After a few minutes, smell receptors undergo sensory adaptation and no longer respond to the chemical, and the patient can no longer smell the odor.

You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it?

Very Good!


31-12

Tongue and Sense of Taste

• Gustatory receptors – located on taste buds

• Taste buds– Location

• Papillae of the tongue• Roof of mouth• Walls of throat

Tongue

} fewer than on tongue


31-13

Tongue and Sense of Taste (cont.)

• Taste cells and supporting structures– On taste buds

– Supporting structures fill in space

– Taste cells • Chemoreceptors• Chemicals in food and drink must be

dissolved in saliva to activate Tongue


31-14


• Taste sensation – 4 primary

• Sweet – tip • Sour – sides • Salty – tip and

sides• Bitter – back

• Umami – 5th basic taste – Glutamic acid

• Spicy foods– Activate pain

receptors– Interpreted by brain

as “spicy”Tongue


31-15

Back


31-16


Activation of taste cells

Cranial nerves

Gustatory cortex of cerebruminterprets information

Taste sensation


31-17


What are the four primary taste sensations and where are their corresponding taste cells located?

ANSWER: The four primary taste sensations are:

Sweet – concentrated on the tip of the tongue

Sour – concentrated on the sides of the tongue

Salty – concentrated on the tip and sides of the tongue

Bitter – concentrated on the back of the tongue


31-18

Eye and Sense of Sight

• Vision system– Eyes

– Optic nerves

– Vision centers in the brain

– Accessory structures

• Eye – Processes light

to produce images

– Three layers

– Two chambers

– Specialized parts


31-19

Eye and Sense of Sight (cont.)

• Outer – sclera – White of the eye – Protects the eye– Sense receptors– Cornea

• Front of eye• “Window” that allows

light into eye• Bends light as it enters

Eye


31-20


• Middle – choroid – Contains blood

vessels– Iris

• Colored part of eye• Muscle that

contracts and relaxes to open or close pupil

• Regulates the amount of light that enters the eye

– Ciliary body• Muscles • Controls the shape

of the lens

– Lens • Posterior to iris• Focuses light on

retina– Accommodation

Eye


31-21


• Inner – retina– Visual receptors

• Rods – Sensitive to light – Will function in dim

light – “limited” night vision

– Do not provide sharp image or detect color

• Cones– Function in bright

light– Sensitive to color

and provide sharp images

– Optic disc – optic nerve enters retina

Eye


31-22


• Chambers of the eye– Anterior chamber

• Front of lens• Filled with aqueous humor – nourishes and

bathes anterior eye

– Posterior chamber• Behind lens• Contains vitreous humor – maintains shape of

eyeball and holds retina in place

Eye


31-23

Back


31-24

Visual Accessory Organs

• Eye orbits– Eye sockets – Form a protective

shell around the eyes

– Eyebrows protect eyes

• Eyelids – Skin, muscle, and

connective tissue– Blinking

• Prevents surface from drying out

• Keeps foreign material out of eye


31-25

Visual Accessory Organs (cont.)

• Conjunctivas – Mucous membranes – Line inner surfaces

of eyelids

• Lacrimal apparatus– Lacrimal glands

• Lateral edge of eyeballs

• Produce tears

– Nasolacrimal ducts

• Medial aspect of eyeballs

• Drain tears into nose


31-26

Visual Accessory Organs (cont.)

• Extrinsic eye muscles–Six per eye move the eyeball

• Superiorly

• Inferiorly

• Laterally

• Medially


31-27

Opticchiasm

Visual Pathways

• Eye works like a camera– Light enters the eye through the lens– Refraction – cornea, lens, and fluids bend

light to focus it on the retina

Opticnerve

Occipital lobe of

cerebrum

Retina convertslight to nerve

impulse

Image upside down on retina Image turned

right-side up


31-28

Eye Safety and Protection

• 90% of eye injuries are preventable– Eye safety practices

• Adequate lighting/handrails• Pad or cushion sharp edges on furniture• Toys should be age-appropriate• Do not mix chemicals

– Proper protective wear• Goggles• Sports eye guards


31-29


Matching:___ Middle layer of eye A. Lacrimal glands___ Eye sockets B. Aqueous humor___ Control shape of lens C. Retina___ Outer layer of eye D. Sclera___ Anterior chamber E. Vitreous humor___ Tears F. Ciliary body___ Bending of light G. Choroid___ Posterior chamber H. Orbits___ Inner layer of eye I. Refraction

I

H

F

E

D

C

BA

G

ANSWER:

Out of Sight!


31-30

The Aging Eye• Eyelids may droop • Quality and quantity

of tears decrease• Conjunctiva thins and

eyes may become dryer

• Cornea yellows, fat deposits around it

• Brown spots on sclera• Pupils become

smaller

• Lens denser and more rigid

• Lens yellows• Retinal changes – vision

fuzzy• Changes in ability of eye

to adapt to light• Impaired night vision• Decreased peripheral

vision; depth perception• Floaters or flashes of light


31-31

Preventing Falls in the Elderly

• Falls can result in fractures of major bones

• Complications of falls can lead to death

• Prone to falling – Vision problems– Poor health– Slower reflexes

• Patient education– Safety checklist– Precautions

– Equilibrium problems– Medication


31-32


What vision changes can occur in the elderly patient?

ANSWER: An elderly patient may have difficulty seeing because of drooping eyelids. Focusing may be more difficult because less light enters the eye. He may have difficulty distinguishing colors due to yellowing of the lens. Vision may be fuzzy because of changes in the retina. Night vision can become impaired. The patient may see floaters or “sparks.”

Nice job!


31-33

Vision Testing

• Professionals include– Ophthalmologist – medical doctor who

is an eye specialist

– Optometrist – provides vision screening and diagnostic testing

– Opticians – fills vision prescriptions for glasses and contacts


31-34

Vision Screening Tests• Myopia – impairment

of distance vision– Eyeball is too long – Light focuses anterior

to retina– Snellen chart– Normal vision

• 20/20

• Hyperopia – impairment of near vision – Eyeball is shorter – Light focused posterior

to retina– Test using a handheld

chart with various sizes of print

– Presbyopia • Impairment due to

aging• Loss of lens elasticity


31-35

Vision Screening Tests (cont.)

• Contrast sensitivity– Distinguish shades of

gray

– Testing• Pelli-Robson contrast

sensitivity chart

• Vistech Consultants vision contrast system

– Detect cataracts or retinal problems before sharpness is impaired

• Color vision – Color-blindness

• May be inherited• More common in

males

– Tests• Ishihara color system• Richmond

pseudoisochromatic color test

– Difficulties may indicate retinal or optic nerve disease


31-36


What is the difference between myopia and hyperopia and what is presbyopia? What effect does each have on vision?

ANSWER: If the patient has myopia, the eyeball is elongated and light focuses in front of the retina. She will have difficulty seeing far away. If she has hyperopia, the eyeball is shorter than normal and light focuses behind the retina. With presbyopia, the lens loses elasticity due to aging, resulting in the inability to see things close up.

Reyeght!


31-37

Treating Eye Problems

• Delicate organ – caution and sterile technique necessary

• Patient education on preventive care

• Administration of medications– Only ophthalmic

medications– Avoid touching

dropper or ointment tube to the eye

• Eye irrigation – Sterile solution– Purpose

• Remove foreign material

• Relieve discomfort


31-38

Common Diseases and Disorders

Disorder/Disease Description

Amblyopia Lazy eye; one eye is not used regularly; poor depth perception; often concurrent with strabismus

Astigmatism Cornea or lens has abnormal shape; blurred images

Cataracts Opaque structures in lens prevent light from passing through; vision fuzzy

Conjunctivitis Pink eye; highly contagious bacterial infection


31-39

Common Diseases and Disorders (cont.)


Dry eye syndrome Common problem; decreased production of oil in tears

Entropion Inversion of lower eyelid

Glaucoma Increase in intraocular pressure due to a buildup of aqueous humor in anterior chamber

Hyperopia Farsightedness


31-40



Macular degeneration

Progressive disease; inadequate blood supply to retina; most common cause of vision loss; affects people over 50 years

Myopia Nearsightedness

Nystagmus Rapid, involuntary eye movements


31-41



Presbyopia Loss of lens elasticity; develops with age

Retinal detachment Layers of retina separate; medical emergency

Strabismus

Convergent

Divergent

Misalignment of eyes

Crossed eyes; one or both eyes turn inward

Wall eye; one or both eyes turn outward


31-42


It is okay to use any solution or medication in the eye?

ANSWER: Only medications or solutions specifically designated for ophthalmic use may be used in the eyes. Medications not designated for the eye may be too concentrated or contain substances that can injure the eye. Solutions should be sterile and care must be taken not to contaminate the tip of the dropper or bottle.


31-43

The Ear

• External ear– Auricle (pinna)

• Collects sound waves

– External auditory canal• Guides sound wave to tympanic membrane

– Tympanic membrane• Separates external canal and middle ear• Vibrates when sound hits it

Ear


31-44

The Ear (cont.)

– Eustachian tube• Connects middle ear

to throat• Equalizes pressure

on eardrum

– Oval window• Separates middle ear

from inner ear

Ear

• Middle ear– Ear ossicles

• Malleus• Incus• Stapes

– Ossicles vibrate in response to vibration of tympanic membrane


31-45

The Ear (cont.)

• Inner ear – labyrinth of communicating chambers– Semicircular canals – detect balance

of the body

– Vestibule – equilibrium

– Cochlea • Hearing receptors

– Organ of Corti – organ of hearing

Ear


31-47

Equilibrium

• Head movement causes fluid in semicircular canals and vestibule to move

• Equilibrium receptors transmit information along vestibular nerves to cerebrum

• Cerebrum determines if body needs to make adjustments


31-48

Sense of Hearing

• Sound waves collected

• Waves cause tympanic membrane to vibrate

• Ossicles amplify vibrations, which enter inner ear

• Movement of hairs lining cochlea trigger nerve impulses

• Impulses are transmitted by auditory nerve to the brain for interpretation


31-49

Sense of Hearing (cont.)

• Bone conduction– Alternative pathway– Bypasses external

and middle ear directly to inner

– Useful in determining cause of hearing problem


31-50


Matching:

___ Pinna A. Organ of Corti

___ Malleus, incus, and stapes B. Cerumen

___ Hearing receptors C. Ear ossicles

___ Inner ear D. Tympanic membrane

___ Organ of hearing E. Auricle

___ Earwax F. Cochlea

___ Eardrum G. Labyrinth

___ Detect balance of body H. Semicircular canalsH

G

F

D

C

B

A

E

ANSWER:


31-51

How to Recognize Hearing Problems in Children

• Guidelines – Infants to 4 months

• Startled by loud noises• Recognize mother’s voice

– 4 to 8 months• Regularly follow sounds• Babble at people

– 8 to 12 months• Respond to the sound of their

name• Respond to “no”


31-52

The Aging Ear

• External ear larger / earlobe longer

• Cerumen dryer and prone to impaction

• Ear canal narrower

• Eardrum shrinks and appears dull and gray

• Ossicles do not move as freely

• Semicircular canals less sensitive to changes in position – affects balance


31-53


What problem with the aging ear makes the elderly more prone to falls?

ANSWER: The semicircular canals become less sensitive to change in position, which affects balance. This problem with equilibrium results in increased chance of falls in the elderly.

Great Answer!


31-54

Hearing Loss• Symptom of a disease, not a normal part of

aging• Conductive hearing loss

– Interruption in transmission to inner ear

– Causes • Obstruction of ear canal• Infection of middle ear• Reduced movement of

stirrup

• Sensorineural hearing loss– Sound waves not perceived

by brain as sound– Causes

• Hereditary• Repeated exposure to

loud noises/viral infections• Side effect of medication


31-55

Hearing Loss (cont.)

• Noise pollution – causes damage to sensitive cells in cochlea

• Working with the hearing-impaired patient– Speak at a reasonable volume, in clear, low-pitched

volumes– Face the person; use hand gestures, if appropriate – Do not overemphasize lip movements– Have patient repeat message to verify understanding– Treat hearing-impaired patients with patience and

respect


31-56

Hearing and Diagnostic Tests

• Hearing tests– Tuning forks – differentiate between types of

loss– Audiometer – measures hearing acuity

• Diagnostic testing– Tympanometry

• Measures the ability of the eardrums to move • Detects diseases and abnormalities of the middle

ear


31-57


Identify the types of hearing loss based on the description below. What can be used to differentiate between the two?

Sound waves not perceived by brain as sound

Causes Hereditary Repeated exposure to loud

noises/viral infections Side effect of medication

Interruption in transmission to inner ear

Causes Obstruction of ear canal Infection of middle ear Reduced movement of

stirrup

Answer:

Conductive hearing loss Sensorineural hearing loss

Bravo!

A tuning fork is a simple test to distinguish between types of hearing loss.


31-58

Treating Ear and Hearing Problems

• Patient education – Preventative ear care– Administer ear medications

• Medications and irrigation– Relieve inflammation or irritation of canal– Loosen and remove impacted cerumen or

foreign body


31-59

Treating Ear and Hearing Problems (cont.)

• Hearing aids– Obtaining a hearing aid

• Otologist – medical doctor specializing in health of ear

• Audiologist – evaluates and corrects hearing problems

– Care and use• Batteries

• Routine cleaning

• Keep dry and avoid hair sprays

• Other devices / strategies– Amplifiers – Closed-captioning– Appliances that light up as

well as ring


31-60


Disorder/Disease DescriptionCerumen impaction Build up of wax within external auditory canal

Hearing loss Deafness

Ménière's disease Disturbance in equilibrium characterized by vertigo and tinnitus


31-61


Disorder/Disease DescriptionOtitis

Otitis externa

Otitis media

Otitis interna

Inflammation of the ear

Swimmers’ ear

Middle ear infection; common infection

Labyrinthitis; inner ear infection

Osteosclerosis Immobilization of the stapes; common cause of conductive hearing loss

Presbycusis Hearing loss due to aging process


31-62


True or False:

___ An audiologist is a physician that specializes in ear health.

___ Otitis media is also called swimmers’ ear.

___ Presbycusis is hearing loss due to the aging process.

___ Vertigo is ringing in the ears.

___ Otitis interna is an inflammation of the labyrinth.

___ Ménière's disease is characterized by disturbances in equilibrium.

___ Otosclerosis is the immobilization of the stapes.

___ Tinnitus is dizziness.F

F

F

T

T

T

T

F

ANSWER:

otologist

externa

Tinnitus

Vertigo


31-63

In Summary31.1 Olfactory receptors, which are the sense receptors for

the sense of smell, are found in the olfactory organ located in the upper part of the nasal cavity.

31.2 When the olfactory receptors are activated, they send information to the olfactory nerves, then on to the cerebellum for interpretation.

31.3 Gustatory receptors are found on the taste buds, which are located on the papillae (bumps) of the tongue.


31-64

In Summary (cont.)

31.4 Gustatory receptors are chemoreceptors which are activated by the chemicals found in food and drink as they are dissolved in the mouth’s saliva. The information is brought to the gustatory cortex of the parietal lobe of the brain for interpretation.

31.5 The four primary taste sensations are, sweet, salty, sour and bitter. Each has a “specialized” area of the tongue where each taste is most pronounced. The fifth recognized taste sensation is umami.


31-65

In Summary (cont.)

31.6 The eye is composed of three layers. The sclera is the outer protective layer and includes the cornea. The middle vascular layer is the choroid, consisting of the iris, pupil, ciliary body, and lens, and is the area of light regulation and focusing. The innermost layer is the retina containing the rods and cones, the optic nerve, and optic disk. This is where the nerve impulse is picked up and brought to the brain for interpretation. The accessory organs are the orbits, eyelids, conjunctivas, lacrimal apparatus, and extrinsic eye muscles, all of which are protective for the eye.


31-66

In Summary (cont.)

31.7 The cornea, lens, and fluids focus light on the retina. The retina converts the image into nerve impulses, which are transmitted by the optic nerve to the brain for interpretation.

31.8 Eye safety and injury prevention includes, but is not limited to, adequate lighting and availability of hand rails, keeping personal and sharp items out of reach of children, wearing of safety goggles when operating power equipment and using chemicals, and not mixing cleaning agents.


31-67

In Summary (cont.)

31.9 Changes in the aging eye include, but are not limited to, diminishing fat tissue, decreased tear production, thinner and dryer conjunctiva, brown spots in the sclera, changes in the iris resulting in smaller pupil, lens becoming denser and more rigid, as well as lens and retinal changes causing fuzziness of vision and difficulty distinguishing colors.

31.10 Ophthalmologists (M.D.), optometrists (O.D.), and opticians are all professionals who deal with eye and vision health.


31-68

In Summary (cont.)

31.11 All treatments for eye problems include use of sterile technique and extreme caution to protect the delicate tissues of the eye. Eye irrigations and medication installations are common treatments. Instruction on these techniques will take place in the Drug Administration chapter.


31-69

In Summary (cont.)

31.12 Common diseases and disorders of the eye include amblyopia, astigmatism, cataracts, conjunctivitis, hyperopia, myopia and presbyopia. More detailed information on the signs, symptoms, and treatments for these conditions, as well as other common eye disorders, is found in the Pathophysiology section of this chapter, directly after the A&P section on the eye.


31-70

In Summary (cont.)

31.13 There are three parts to the ear. The external ear includes the auricle or pinna and external auditory canal to the tympanic membrane. The middle ear begins at the tympanic membrane and ends at the oval window and includes the ear ossicles. The inner ear is composed of the labyrinth and contains the organ of Corti as well as perilymph and endolymph, the fluids of hearing.

31.14 The semicircular canals and vestibule in the inner ear function in the equilibrium and balance of the body, sending impulses to the vestibular nerves, which transmit information to the cerebrum for interpretation.


31-71

In Summary (cont.)

31.15 The outer ear collects sound waves and channels them to the tympanic membrane, which vibrates. The vibrations are amplified by the ear ossicles and enter the inner ear and cochlea. The movements of the hairs in the cochlea trigger nerve impulses that are transmitted by the auditory nerve to the brain.

31.16 Aging causes the eardrum to shrink. The joints between the ossicles degenerate so there is less freedom of movement, which causes decrease in hearing acuity.


31-72

In Summary (cont.)

31.17 Conductive hearing loss is the result of sound wave transmission interruption, as with cerumen impaction and tumors or infections. Sensorineural hearing loss is the result of nerve damage so that the brain cannot perceive sounds waves as sound.

31.18 Ear treatments depend on the condition being treated, but may include ear irrigation and medication installation as well as hearing aids and/or surgery for hearing loss.


31-73

In Summary (cont.)

31.19 Preventative ear care includes, but is not limited to, routine hearing exams; avoiding the insertion of small items into the ear canal; and using care when using cotton swabs. Ear protection should be used when exposed to loud or prolonged noise. Use medications such as ear drops properly and watch for signs of ear or hearing problems.


31-74

In Summary (cont.)

31.20 The pathophysiology section on ear and hearing diseases and conditions is found at the end of the A&P section for the ear. Signs, symptoms, and treatments of cerumen impaction, hearing loss, Ménière's disease, otitis, otosclerosis, and other common problems are outlined in this section.


31-75

Every closed eye is not sleeping, and every open

eye is not seeing.

~ Bill Cosby

End of Chapter 31

chapter © 2011 the mcgraw-hill companies, inc. all rights reserved. 31 special senses

Documents

mcgrawhill companies

tongue slide

odor slide

primary taste sensations

corresponding taste

smell sensations

olfactory organ slide

tongue sour