Special Senses
PowerPoint® presentation to accompany:
Medical Assisting
Third Edition
Booth, Whicker, Wyman, Pugh, Thompson
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-2
Learning Outcomes
35.1 Describe the anatomy of the nose and the function
of each part.
35.2 Describe how smell sensations are created and
interpreted.
35.3 Describe the anatomy of the tongue and the function
of each part.
35.4 Describe how taste sensations are created and
interpreted.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-3
Learning Outcomes (cont.)
35.5 Name the four primary taste sensations and the
acknowledged fifth taste sensation.
35.6 Describe the anatomy of the eye and the function of
each part, including the accessory structures and
their functions.
35.7 Trace the visual pathway of through the eye and to
the brain for interpretation.
35.8 Identify ways that patients can practice preventive
eye care.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-4
Learning Outcomes (cont.)
35.9 State ways that vision changes with age.
35.10 List the medical professionals involved in diagnosis
and treatment of visual disorders, including the
roles that each play in patient care.
35.11 List treatments for eye visual disorders.
35.12 Describe the causes, signs and symptoms, and
treatments of various diseases and conditions of the
eye.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-5
Learning Outcomes (cont.)
35.13 Describe the anatomy of the ear and the function
of each part.
35.14 Explain the role of the ear in maintaining
equilibrium.
35.15 Explain how sounds travel through the ear and are
interpreted in the brain.
35.16 State ways that hearing changes with age.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-6
Learning Outcomes (cont.)
35.17 List the types of hearing loss and how they differ.
35.18 Describe treatments for ear and hearing disorders.
35.19 Explain how patients can be educated about
preventive ear care.
35.20 Describe the causes, signs and symptoms, and
treatments of various disorders of the ear and
hearing.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-7
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-8
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-9
Nose and Sense of Smell (cont)
Smell sensation
Activation of smell receptors 
information sent to olfactory nerves
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-10
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 order
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-11
Apply Your Knowledge
You notice an odor coming from a patient when you
enter the exam room. Why would the patient not be
able to smell it?
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.
Very
Good!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-12
Tongue and Sense of Taste


Gustatory receptors – located on taste
buds
Taste buds

Location



Papillae of the tongue
Roof of mouth
}
fewer than on tongue
Walls of throat
Tongue
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-13
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-14
Tongue and Sense of Taste (cont.)

Taste sensation



4 primary




Sweet – tip
Sour – sides
Salty – tip and
sides
Bitter – back
Unami


5th basic taste
Glutamic acid
Spicy foods


Activate pain
receptors
Interpreted by brain
as “spicy”
Tongue
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-15
Back
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-16
Tongue and Sense of Taste (cont.)
Taste sensation
Activation of
taste cells
Cranial
nerves
Gustatory cortex of cerebrum
interprets information
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-17
Apply Your Knowledge
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-18
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

© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-19
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
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35-20
Eye and Sense of Sight (cont.)

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
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35-21
Eye and Sense of Sight (cont.)

Inner – retina


Visual receptors

Cones

Rods



Sensitive to light
Will function in
dim light –
“limited” night
vision
Do not provide
sharp image or
detect color


Function in bright
light
Sensitive to color
and provide sharp
images
Optic disc – optic
nerve enters retina
Eye
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-22
Eye and Sense of Sight (cont.)

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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-23
Back
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-24
Eye and Sense of Sight:
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-25
Eye and Sense of Sight:
Visual Accessory Organs (cont.)

Conjunctivas


Mucus 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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-26
Eye and Sense of Sight:
Visual Accessory Organs (cont.)

Extrinsic eye muscles

Six per eye move the eyeball
Superiorly
 Inferiorly
 Laterally
 Medially

© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-27
Eye and Sense of Sight:
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
Image upside
down on retina
Retina converts
light to nerve
impulse
Image turned
right-side up
Optic
nerve
Optic
chiasm
Occipital
lobe of
cerebrum
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-28
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

© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-29
Apply Your Knowledge
Matching: ANSWER:
___
G Middle layer of eye
H Eye sockets
___
___
F Control shape of lens
___
D Outer layer of eye
___
B Anterior chamber
A Tears
___
___
I Bending of light
___
E Posterior chamber
C Inner layer of eye
___
A.
B.
C.
D.
E.
F.
G.
H.
I.
Lacrimal glands
Aqueous humor
Retina
Sclera
Vitreous humor
Ciliary body
Choroid
Orbits
Refraction
Out of
Sight!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-30
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-31
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


Equilibrium problems
Medication
Patient education


Safety checklist
Precautions
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-32
Apply Your Knowledge
What vision changes can occur in the elderly patient?
ANSWER: An elder 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!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-33
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
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35-34
Vision Testing: 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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-35
Vision Testing: Screening Tests (cont.)

Contrast sensitivity

Distinguish shades of gray

Testing



PelliRobson contrast
sensitivity chart

Color vision






May be inherited
More common in
males
Tests

Vistech Consultants vision
contrast system
Detect cataracts or retinal
problems before sharpness
is impaired
Color-blindness
Ishihara color system
Richmond
pseudoisochromatic
color test
Difficulties may
indicate retinal or optic
nerve disease
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-36
Apply Your Knowledge
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!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-37
Treating Eye Problems



Delicate organ – caution and sterile technique
necessary
Patient education on preventive care
Administration
 Eye irrigation
of medications
 Sterile solution


Only ophthalmic
medications
Avoid touching
dropper or ointment
tube to the eye

Purpose


Remove foreign
material
Relieve discomfort
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-38
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
Opaque structures in lens prevent light
from passing through; vision fuzzy
Cataracts
Conjunctivitis
Pink eye; highly contagious bacterial
infection
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-39
Common Diseases and Disorders
(cont.)
Disorder / Disease Description
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-40
Common Diseases and Disorders
(cont.)
Disorder / Disease Description
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-41
Common Diseases and Disorders
(cont.)
Disorder / Disease Description
Prespyopia
Loss of lens elasticity; develops with age
Retinal
detachment
Layers of retina separate; medical
emergency
Strabismus
Convergent
Misalignment of eyes
Crossed eyes; one or both eyes turn
inward
Wall eye; one or both eyes turn outward
Divergent
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-42
Apply Your Knowledge
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.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-43
The Ear and the Senses of Hearing
and Equilibrium: Structures

External ear

Auricle (pinna)


External auditory canal


Collects sound waves
Guides sound wave to tympanic membrane
Tympanic membrane


Separates external canal and middle ear
Vibrates when sound hits it
Ear
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-44
The Ear and the Senses of Hearing
and Equilibrium: Structures (cont.)

Middle ear

Ear ossicles





Malleus
Incus
Stapes
Ossicles vibrate in
response to vibration
of tympanic
membrane
Eustachian tube



Connects middle ear
to throat
Equalizes pressure on
eardrum
Oval window

Separates middle ear
from inner ear
Ear
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35-45
The Ear and the Senses of Hearing
and Equilibrium: Structures (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
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35-47
The Ear and the Senses of Hearing
and Equilibrium: Structures (cont.)

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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-48
The Ear and the Senses of Hearing
and Equilibrium: Hearing Process





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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-49
The Ear and the Senses of Hearing
and Equilibrium: Hearing Process (cont.)

Bone conduction



Alternative pathway
Bypasses external and
middle ear directly to
inner
Useful in determining
cause of hearing
problem
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-50
Apply Your Knowledge
Matching:
ANSWER:
___
E Pinna
A. Organ of Corti
___
C Malleus, incus, and stapes
B. Cerumen
___
F Hearing receptors
C. Ear ossicles
___
G Inner ear
D. Tympanic membrane
___
A Organ of hearing
E. Auricle
___
B Earwax
F. Cochlea
___
D Eardrum
G. Labyrinth
___
H Detect balance of body
H. Semicircular canals
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-51
How to Recognize Hearing Problems
in Children

Guidelines

Infants to 4 months



4 to 8 months



Startled by loud noises
Recognize mother’s voice
Regularly follow sounds
Babble at people
8 to 12 months


Respond to the sound their name
Respond to “no”
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-52
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-53
Apply Your Knowledge
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!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-54
Hearing Loss


Symptom of a disease, not a normal part of aging
Conductive hearing loss  Sensorineural hearing loss


Interruption in
transmission to inner ear
Causes
 Obstruction of ear canal
 Infection of middle ear
 Reduced movement of
stirrup


Sound waves not perceived
by brain as sound
Causes
 Hereditary
 Repeated exposure to
loud noises / viral
infections
 Side effect of medication
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35-55
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-56
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-57
Apply Your Knowledge
Identify the types of hearing loss based on the description
below. What can be used to differentiate between the two?
Answer:
A tuning fork is a simple test to distinguish between types of
hearing loss.
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


Bravo!
Sound waves not perceived by
brain as sound
Causes

Hereditary

Repeated exposure to loud
noises / viral infections

Side effect of medication
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-58
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
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-59
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
Other devices / strategies



Amplifiers
Closed-captioning
Appliances that light up as
well as ring
Care and use



Batteries
Routine cleaning
Keep dry and avoid hair sprays
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-60
Common Diseases and Disorders
Disorder /
Disease
Description
Cerumen
impaction
Build up of wax within external auditory
canal
Hearing loss
Deafness
Meniere’s disease Disturbance in equilibrium characterized
by vertigo and tinnitus
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-61
Common Diseases and Disorders
Disorder /
Disease
Description
Otitis
Otitis externa
Otitis media
Otitis interna
Osteosclerosis
Inflammation of the ear
Swimmers’ ear
Middle ear infection; common infection
Labyrinthitis; inner ear infection
Immobilization of the stapes; common
cause of conductive hearing loss
Presbycusis
Hearing loss due to aging process
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-62
Apply Your Knowledge
True or False:
ANSWER:
___
F An audiologist is a physician that specializes in ear health.
___
F Otitis media is also called swimmers’ ear.
otologist
externa
___
T Presbycusis is hearing loss due to the aging process.
___
F Vertigo is ringing in the ears. Tinnitus
___
T Otitis interna is an inflammation of the labyrinth.
___
T Meniere’s disease is characterized by disturbances in equilibrium.
___
T Otosclerosis is the immobilization of the stapes.
___
F tinnitus is dizziness. Vertigo
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-63
In Summary

Special senses detect changes in the environment


Each works with the nervous system to enable the body
to cope with environmental changes
Medical assistant’s knowledge of senses



Provide eye and ear care to patient
Patient education
Meet needs of children, elderly, and patients with
impairments
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
35-64
End of Chapter
Every closed eye
is not sleeping,
and every open
eye is not seeing.
~ Bill Cosby
© 2009 The McGraw-Hill Companies, Inc. All rights reserved