PowerPoint® to accompany
Medical Assisting
Chapter 33
Second Edition
Ramutkowski  Booth  Pugh  Thompson  Whicker
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
The Special Senses System
Objectives (cont.)
33-1 Spell, define, and correctly use the Key Terms in
this chapter.
33-2 Describe the anatomy of the nose and the function
of each part.
33-3 Describe how smell sensations are created and
interpreted.
33-4 Describe the anatomy of the tongue and the
function of each part.
2
The Special Senses System
Objectives (cont.)
33-5 Describe how taste sensations are created and
interpreted.
33-6 Name the four primary taste sensations.
33-7 Describe the anatomy of the eye and the function
of each part.
33-8 Describe various disorders of the eye.
33-9 Trace the path of a visual image through the eye
and to the brain for interpretation
3
The Special Senses System
Objectives (cont.)
33-10 Describe the anatomy of the ear and the function
of each part.
33-11 Describe various disorders of the ear.
33-12 Explain how sounds travel through the ear and
are interpreted in the brain.
33-13 Explain the role of the ear in equilibrium.
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Introduction
Special senses that have sensory receptors
located within relatively large, sensory
organs in the head;
 Nose – smell
 Tongue – taste
 Eyes – vision
 Ears – hearing and equilibrium
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Nose
 Smell receptors
 Olfactory receptors
 Chemoreceptors
 Respond to changes in
chemical
concentrations
 Chemicals must be
dissolved in the mucus
of the nose to activate
smell receptors
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Smell Sensation
Smell receptors are activated, they send their
information to the olfactory nerves
send the information along olfactory
bulbs and tracts
different areas of the cerebrum
cerebrum interprets the information as a
particular type of smell
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Smell Sensation (cont.)
 Smell undergoes sensory adaptation
 Same chemical can only stimulate smell
receptors for a limited amount of time
 Smell receptors no longer respond to the
chemical and you can no longer smell
 You smell perfume when you first
encounter it but in a few minutes, you no
longer smell it.
8
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?
9
Apply Your Knowledge -Answer
You notice an odor coming from a
patient when you enter the exam room.
Why would the patient not be able to
smell it?
After a few minutes, smell receptors no
longer respond to the chemical and the
patient can no longer smell the odor.
10
Tongue
 Taste or gustatory
receptors –taste buds
 Found on "the bumps"
of the tongue
(papillae)
 Taste buds are
microscopic
 Also on roof of your
mouth and walls of
your throat
Click for Larger View
11
Tongue (cont.)
12
Taste Sensation
 Four types of taste cells - activated by a
particular group of chemicals




Sweet - tip of the tongue.
Sour - sides of the tongue.
Salty - tip and sides of the tongue.
Bitter - back of the tongue
13
Eye
 Outer layer
 Sclera
 Cornea
 Middle layer
 Choroid
 Iris
 Ciliary body
 Inner layer
 Retina – contains rods
and cones
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Eye (cont.)
Outer layer:
 Sclera is the “white of the eye” and does not allow
light to enter the eye
 Cornea - anterior to the sclera
 Allows light to enter the eye (“window of the eye”)
 Contains sensory receptors can detect even the
smallest of particles
15
Eye (cont.)
Middle layer:




Also called vascular and pigmented layer
Richly supplied with blood vessels and pigments
Choroid lines the sclera and absorb extra light
Ciliary body functions to hold and move the lens to
focus the eye.
 Cloudy areas on the lens are called “cataracts.”
 Hole in iris is called the pupil.
16
Eye (cont.)
Inner layer:




Also called the retina
Richly supplied with blood vessels and pigments
Contains visual receptors called rods and cones
Rods allow us to detect black, white, and gray
shades and images in dim light.
 Cones allow us to see images in bright light
 Cones allow us to see color.
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Eye (cont.)
 Eyelid - skin, muscle,
and dense connective
tissue.
 Orbicularis oculi
muscle and is responsible
for blinking
 Conjunctivas - mucous
membranes
 Line the inner surfaces of
the eyelids
 Fold back onto the anterior
surface of each eyeball
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Eye (cont.)









Vitreous humor
Lens
Choroid
Sclera
Retina
Pupil
Iris
Cornea
Conjunctiva
Draw a line to each part of the eye.
19
Tears
Lacrimal apparatus
consists of lacrimal glands
and nasolacrimal ducts.
Lacrimal glands are on the
lateral edge of each eyeball and
they produce tears.
 Mostly water but also
contain enzymes that can
destroy bacteria and viruses
 Outer oily layer that
prevents them from
evaporating
When a person cries, the abundance of tears entering the nose
produces the “runny nose” associated with crying.
20
Eye Muscles
Extrinsic eye muscles are
skeletal muscles that
move the eyeball
Each eyeball has 6
extrinsic eye muscles
attached to them that
move the eyeball




Superiorly
Inferiorly
Laterally
Medially
21
Process of Seeing
Eye works like a camera
 light passes through the
cornea, pupil, lens and
fluids of the eye, which
focuses the light onto
the retina
 The image is projected
upside down on the
retina
 Retina converts the
light into nerve
impulses that are sent
to the brain
The brain interprets these impulses, turns the image rightside up and develop a picture of the object.
22
Parts of the Eye
Choroid
Ciliary Body
Absorbs extra light in
eye
Holds lens, moves lens
for focusing
Iris
Controls amount of light
entering eye
Lens
Focuses light onto retina
23
Parts of the Eye (cont.)
Retina
Contains visual receptors
Rods
Allow vision in dim light,
detect black-and-white
images, detect broad outlines
of images
Allow vision in bright light,
detect colors, detect details
Cones
Optic Nerve
Carries visual information
from rods and cones toward
the brain
24
Parts of the Eye (cont.)
Aqueous Humor nourishes structures in
anterior eye cavity
Vitreous Humor holds retina in place;
maintains shape of
eyeball
25
Eye Disorders (cont.)
 Common eye problems



Conjunctivitis - inflammation of the conjunctiva
Blepharitis - inflammation of the eyelid
Corneal abrasions - scratching of the cornea
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Eye Disorders (cont.)
Astigmatism - cornea has
an abnormal shape
which causes blurred
images during distant or
near vision.
Amblyopia - commonly
called “lazy eye”
Cataracts - structures in the
lens that prevent light
from going through the
lens
Dry Eye Syndrome one of the most
common eye
problems treated by
physicians
Glaucoma - condition in
which too much
pressure is created in
the eye by excessive
aqueous humor
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Eye Disorders (cont.)
Hyperopia - called
farsightedness
Myopia - called
nearsightedness
Presbyopia - a common
eye disorder that
develops with age difficulty seeing objects
close up
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Eye Disorders (cont.)
Macular Degeneration a progressive disease that
usually affects people
over 50.
 It occurs when the
retina no longer receives
an adequate blood supply.
Retinal Detachment occurs when the layers of
the retina separate.
 Considered a medical
emergency and if not
treated right away, leads to
permanent vision loss.
29
Eye Safety and Protection Works
Common eye injuries that occur while
playing a sport include:






Scratched corneas
Inflamed iris
Bleeding in the anterior eye chamber
Traumatic cataracts
Inflamed retinas
Eye socket fractures
30
The Ear
 External ear


Auricle
Tympanic membrane
 Middle ear



Malleus
Stapes
Incus
 Inner ear - labyrinth


Cochlea
Semicircular canals
31
The Ear (cont.)
 Auricle
 Tympanic
membrane
 Ear canal
 Eustachian tube
 Auditory nerve
 Cochlea
 Semicircular
canals
Draw a line to each part of the ear.
32
Hearing Process
 Movement of the hairs
 Sound enters the
triggers nerve
external ear which
impulses.
makes the eardrum
 The impulses are
vibrate
transmitted via
 The middle ear
auditory nerve to the
amplifies the vibrations
brain.
and the waves cause
 The brain perceives the
the tiny hairs in the
sound.
cochlea to bend.
33
Ear and Balance
 Brain constantly monitors the position of
one’s body on the information received from
the semicircular canals, eyes and muscles.
 Change in position is detected by the canal
and passed to the brain
 The brain uses this information to maintain
balance
34
Disorders of the Ear
 Conductive deafness -produced when sound
waves cannot be conducted through the ear
 Sensorineural deafness - produced when neural
structures associated with the ear are damaged
 Tinnitus - ringing in the ear
35
Apply Your Knowledge
What would happen if a patient had
damage to the middle ear?
36
Apply Your Knowledge -Answer
What would happen if a patient had
damage to the middle ear?
The middle ear amplifies the vibrations and the
waves cause the tiny hairs in the cochlea to bend so if
there was damage to this part of the ear, the patient
may have impaired hearing.
37
How to Recognize Hearing
Problems in Children
 Hearing problems in babies and toddlers
are not easy to recognize
 By 4 months the infant should:
 Startle by loud noises (barking dog, handclap, etc.)
 Wake up at the sound of voices.
 Turn head or move eyes to follow a sound
 Recognize the mother’s voice better than
other voices
38
Summary
Medical Assistant
Knowledge of the Special
Senses will assist you in
providing care for the
patient with diseases and
disorders of the special
senses.
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End of Chapter
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